I installed the User & Comment mentioning add-on and it works on a computer, users can tag others but tagging on mobile does not work. Typing @User does not bring up the option to select a user.
It this not supposed to work on mobile?
You should change the value of the "Load Rich Editor" option. Just set it "Mobile and Desktop". More info here: https://wpdiscuz.com/docs/wpdiscuz-7/plugin-settings/comment-form/#load-rich-editor
Note: We don’t recommend disable the rich editor if you have installed wpDiscuz Emoticons and wpDiscuz Comment & User Mentioning addons. These two addons add new toolbar buttons for selecting “Emojis”, “Stickers”, “Users”. If you disable the rich editor, the addons buttons will be disabled as well. We recommend just disable the toolbar formatting buttons using the next option, instead of disabling the whole rich editor.
