Matchframe on the bad frame and make a freeze frame using Duplicated Fields. You may get lucky and get the field that’s not messed up duplicated. Then cut it back into your sequence.
I know the HVX200 and 200a both record to MXF that Avid reads directly. I assume the 500 series camera does too. I’d ask for a few clips of sample footage to test before things get too far ahead. That way you can determine if MXF really is the best option, and what workflow problems you might run into.
Not a clue what it means, but if you just cut that sequence into a new one–may it’s telling you the old sequence had a corruption? Maybe a corrupt media file or render? Putting everything into a new sequence typically fixes weird issues like that.