diff --git a/app/assets/stylesheets/chat.scss b/app/assets/stylesheets/chat.scss
index b83357a43..7f7cee5c1 100644
--- a/app/assets/stylesheets/chat.scss
+++ b/app/assets/stylesheets/chat.scss
@@ -1066,7 +1066,7 @@
   display: none;
   z-index: 1;
   border-top: 1px solid #dbdbdb;
-  bottom: 60px;
+  bottom: 90px;
   width: 100%;
   max-height: 280px;
   overflow-x: scroll;
diff --git a/app/controllers/search_controller.rb b/app/controllers/search_controller.rb
index 65550cad9..d912ab8cf 100644
--- a/app/controllers/search_controller.rb
+++ b/app/controllers/search_controller.rb
@@ -59,7 +59,7 @@ class SearchController < ApplicationController
 
   def chat_channels
     search_user_id = if chat_channel_params[:user_id].present?
-                       [current_user.id, SiteConfig.mascot_user_id]
+                       [current_user.id, SiteConfig.mascot_user_id, chat_channel_params[:user_id]].reject(&:blank?)
                      else
                        [current_user.id]
                      end
diff --git a/app/javascript/chat/__tests__/chat.test.jsx b/app/javascript/chat/__tests__/chat.test.jsx
index 66f1040d4..46a296c39 100644
--- a/app/javascript/chat/__tests__/chat.test.jsx
+++ b/app/javascript/chat/__tests__/chat.test.jsx
@@ -1,5 +1,5 @@
 import { h } from 'preact';
-import { render } from '@testing-library/preact';
+import { fireEvent, render } from '@testing-library/preact';
 import fetch from 'jest-fetch-mock';
 import { JSDOM } from 'jsdom';
 import { axe } from 'jest-axe';
@@ -226,4 +226,19 @@ describe('<Chat />', () => {
       }),
     ).toBeDefined();
   });
+
+  it('should show mention pop-up on keyUp @', async () => {
+    const { getByLabelText, getByTestId } = render(<Chat {...getRootData()} />);
+
+    const inputField = getByLabelText('Compose a message');
+
+    expect(inputField).toBeDefined();
+    fireEvent.change(inputField, { target: { value: '@' } });
+
+    const mentionModal = getByTestId('mentionList');
+    const allButton = getByTestId('all');
+
+    expect(mentionModal).toBeDefined();
+    expect(allButton).toBeDefined();
+  });
 });
diff --git a/app/javascript/chat/chat.jsx b/app/javascript/chat/chat.jsx
index c5d367ac0..e82c4b91d 100644
--- a/app/javascript/chat/chat.jsx
+++ b/app/javascript/chat/chat.jsx
@@ -261,7 +261,7 @@ export default class Chat extends Component {
           activeChannel ||
           this.filterForActiveChannel(channels, activeChannelId),
       });
-      this.setupChannel(activeChannelId);
+      this.setupChannel(activeChannelId, activeChannel);
     } else if (activeChannelId) {
       this.setState({
         scrolled: false,
@@ -273,7 +273,7 @@ export default class Chat extends Component {
           activeChannel ||
           this.filterForActiveChannel(channels, activeChannelId),
       });
-      this.setupChannel(activeChannelId);
+      this.setupChannel(activeChannelId, activeChannel);
     } else if (channels.length > 0) {
       this.setState({
         chatChannels: channels,
@@ -288,6 +288,7 @@ export default class Chat extends Component {
         channels[0].channel_modified_slug,
         channels,
       );
+      this.setupChannels(channels);
     } else {
       this.setState({ channelsLoaded: true });
     }
@@ -323,9 +324,10 @@ export default class Chat extends Component {
   };
 
   setupChannels = (channels) => {
+    const { activeChannel } = this.state;
     channels.forEach((channel, index) => {
       if (index < 3) {
-        this.setupChannel(channel.chat_channel_id);
+        this.setupChannel(channel.chat_channel_id, activeChannel);
       }
     });
   };
@@ -353,8 +355,8 @@ export default class Chat extends Component {
     });
   };
 
-  setupChannel = (channelId) => {
-    const { messages, messageOffset, activeChannel, appDomain } = this.state;
+  setupChannel = (channelId, activeChannel) => {
+    const { messages, messageOffset, appDomain } = this.state;
     if (
       !messages[channelId] ||
       messages[channelId].length === 0 ||
@@ -362,7 +364,11 @@ export default class Chat extends Component {
     ) {
       getAllMessages(channelId, messageOffset, this.receiveAllMessages);
     }
-    if (activeChannel && activeChannel.channel_type !== 'direct') {
+    if (
+      activeChannel &&
+      activeChannel.channel_type !== 'direct' &&
+      activeChannel.chat_channel_id === channelId
+    ) {
       getContent(
         `/chat_channels/${channelId}/channel_info`,
         this.setOpenChannelUsers,
@@ -822,21 +828,26 @@ export default class Chat extends Component {
     if (index > -1) {
       newUnopenedChannelIds.splice(index, 1);
     }
+
+    let updatedActiveChannel = this.filterForActiveChannel(
+      channelList,
+      id,
+      currentUserId,
+    );
+
     this.setState({
-      activeChannel: this.filterForActiveChannel(
-        channelList,
-        id,
-        currentUserId,
-      ),
+      activeChannel: updatedActiveChannel,
       activeChannelId: parseInt(id, 10),
       scrolled: false,
       showAlert: false,
       allMessagesLoaded: false,
+      showMemberlist: false,
       unopenedChannelIds: unopenedChannelIds.filter(
         (unopenedId) => unopenedId !== id,
       ),
     });
-    this.setupChannel(id);
+
+    this.setupChannel(id, updatedActiveChannel);
     const params = new URLSearchParams(window.location.search);
 
     if (params.get('ref') === 'group_invite') {
@@ -1231,6 +1242,7 @@ export default class Chat extends Component {
     <Button
       data-channel-type={type}
       onClick={this.triggerChannelTypeFilter}
+      data-testid={name}
       className={`chat__channeltypefilterbutton crayons-indicator crayons-indicator--${
         type === active ? 'accent' : ''
       }`}
@@ -1634,6 +1646,8 @@ export default class Chat extends Component {
     const { activeChannel } = this.state;
     const mention = e.keyCode === 64;
     if (mention && activeChannel.channel_type !== 'direct') {
+      const memberListElement = document.getElementById('mentionList');
+      memberListElement.focus();
       this.setState({ showMemberlist: true });
     }
   };
@@ -1687,6 +1701,7 @@ export default class Chat extends Component {
     el.value = `${before + name} ${after}`;
     el.selectionStart = start + name.length + 1;
     el.selectionEnd = start + name.length + 1;
+    el.dispatchEvent(new Event('input'));
     el.focus();
     this.setState({ showMemberlist: false });
   };
@@ -1745,13 +1760,16 @@ export default class Chat extends Component {
       channelUsers,
       memberFilterQuery,
     } = this.state;
+
     const filterRegx = new RegExp(memberFilterQuery, 'gi');
+
     return (
       <div
         className={
           showMemberlist ? 'mention__list mention__visible' : 'mention__list'
         }
         id="mentionList"
+        data-testid="mentionList"
       >
         {showMemberlist
           ? Object.values(channelUsers[activeChannelId])