Today i'm pushing a code change to DashboardFE to fix posts appearing without mention handles, particularly when coming from certain instances. It adds them back to the post and the notification preview.
Grab the code change from the usual channel:
https://notabug.org/daisuke/DashboardFE
If you have it installed there's no need to re-upload everything, you can just replace the file file "functions.php" inside the include folder.
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@pleb Fixed, sorry again 
@hideki that's the real cost of open source, free QA: you want it or not :D
Looks like a neat frontend, thanks for the option to try it out 👍