I don't know precisely what causes this, but it is happening
The only program using the files is Tixati so I believe that when Tixati is sending a piece it doesn't rename them but sometimes, it does?!

Example:
C:\File1.mp4 is 9GB.

Tixati is set to add a .!tix extension to all incomplete files. "$file.!tix."

Tixati is set to "Move individual files immediately upon completion."

Tixati is set to "Directly move file/folder if possible when changing location."

C:\File1.mp4.!tix completes.

Tixati starts moving C:\File1.mp4.!tix to C:\File1.mp4

Sometimes, Tixati simply renames the file. Other times, it will start copying the file to C:\File1.mp4 and if left unattended, C:\ will have both C:\File1.mp4 and C:\File1.mp4.!tix, both completed and usable.
If this behaviour is observed, I need to stop the move, go to C:\ and rename File1.mp4.!tix to File1.mp4 manually. Maybe even Force Check but it hasn't once not returned the file at 100%.

If anymore info is needed, I'm here for anything. Hope this helps the improvement of the program!

Thanx for shareing this info.. I do not use the "$file.!tix" function, and (once) Et transferred
19 GB to my completed files folder ( after some 28 h slow jerking ) allmost all of th files were incomplete wrx or 000000 inside.. so.. other factors may be considered..  it just happens time to time I figure. When all sorts / mp4, html, pdf.. etc. / of things and directory structures are mixed up in one single compressed bundle.. it still can be / 2017 / a giant risk to cope with... so to say. Clean both folders, and the Tixati transferlist data (!) if different.. mounted harddrives (?) are involved check that t o o

the 'copying' you are seeing is completely normal. it just 'copies' in case something happens to the original while copying.

when it does not move to complete folder and/or does not drop incomplete file extension that is a problem. more details would be helpful to solve that.

for this option, if your download folder and seeding/complete folder are on the same drive it can fast move. if they are on different drives, it has to slow move(essentially copy).

What more details would you need? I'm here to offer anything needed.
Tixati inability to simply remove the .!tix extension can happen both in same drive and different drive operations.

It happens most regularly when the file should simply be renamed in the same directory.

when it happens, is it usually a torrent that is a single file or are there multiple files in a folder?
if a folder with multiple files. does it happen to all files or just one?

if you take a torrent that has failed to rename and say delete it and re-download it, does it fail again?