I am a staff user. When I assign somebody to topic using discourse-assign plugin, I always see myself as an assigned person in my activity list (marked as orange twice):
Underlined mention should be a username who has assigned to the topic, shouldn’t it?
Yes, I can repro this. I just assigned that topic to @supermathie, but in my activity it says I assigned it to myself. Other areas of the UX, including the /my/activity/assigned, and the topic itself show the correct assigned user.
I know what the bug is, it is just a nightmare to fix, its on my list when I have a some time to redo a bunch of internals. The root cause is that it is very hard to glue the “who” part to the actual post, we are using custom fields now which is very messy.