not sure how you can screenshot something like this
anyway
MB is portable, version 3.4.7757 P
step by step is
1- have a video file in Inbox
2- open the Tag Editor (Shift+Enter)
3- write "MyTag" in the Artist tag and save
3b - if you go to other files, and start typing "M" in the Artist tag, the autocomplete window will suggest "MyTag"
the problem is
4 - right click, send to Video and close MB
4 - reopen MB and if you go to other files, and start typing "M" in the Artist tag, the autocomplete window doesn't suggest "MyTag" anymore, despite it still being the Artist tag of a file
if you do the same for a music file, and send it to Music Library, it works fine
with a video file, sent to Video, it doesn't