It seems that I have a very similar problem, but maybe I don’t understand how it should behave.
I just installed syncthing on a linux server and on my win10 computer. I set it up to sync a folder in c:\users\username\xxx on the windows machine.
I copied a big file (300MB) in the synced folder.
When I rename the file on the linux machine, the name of the file on windows changes almost immediately (meaning that I can see the .syncthing.xxx.tmp file only for a very short time in the file explorer, then the filename is immediately changed).
When I change the name of the file in windows, and then do some ‘ls’ on the linux machine, I can see the .syncthing.xxx.tmp file much longer. I also see the size of the folder growing progressively, until it reaches twice the size of my big file, and only then the initial file (the one with the old name) is removed.
I deduced that the rename event is well catched by the filesystem watcher in linux, but it isn’t correctly handled in Windows.
This is very disappointing as this would mean if I move or rename the files I want to sync, this will lead to very heavy copy load to get it synced, although it would have taken only a couple of seconds to apply the correct changes.
I tried this using SyncTrayzor or Syncthing-GTK integrations with exactly the same results.
Please help me understanding how to get it work on windows as well.