As the topic says; what exactly does it mean when tixati is "repairing" a piece from multiple peers?
I've been downloading a very large torrent and it seems to be stuck on one last piece (somewhere in the middle) that it perpetually tries to "repair" from multiple peers (including seeds that are marked as complete) but never seems to succeed in. Data is downloaded but the piece never finishes.

I've not been able to find any sort of info what this "repairing" even means and why it's not just trying to redownload from peers that are obviously complete at 100%...?
Is there a way to coerce tixati to stop this "repair" attempt and try to get the piece a normal way?

Yes what is this? It is an extremely slow process compared to DL the piece from a existing fast peer.

Just go to the incomplete pieces folder
e.g. C:\Users\USERNAME\AppData\Roaming\tixati\incomplete-pieces
and delete the subfolders

The Incomplete Pieces folder could be different on your machine.
You can check: Settings > Transfers > Locations > Incomplete Piece Storage Location

Before deleting something make sure you don't use that folder to store other things.

This helped but I'd still call this behavior a bug in tixati that needs actual fixing in the code instead

I surely agree.  I really think the authors need to look into not trying to repair if there are 100% peers out there.  Just request the block from a peer that has it good.  I had one of these go on for a very long time (I forget exactly how long but I was thinking it would never quit) trying to repair when there were complete peers out there.  Please, guys, just think this one through a little bit more.

I use Tixati daily and, for the most part, it is great.  This "repairing" issue and the extreme time it takes to get the last mini-block for a block is annoying.  It will easily take longer to get the very last little bit than to download entire other blocks.  

Mike