If you happen to make a case-only rename of some file on windows machine, then this file will be renamed on this machine only. The filename caseness won’t propagate to other windows machines and the file will become out of sync forever. To deal with this conflict one have to manually rename this file on every machine to match the case.
There is a easier way. If you see that file “types.h” is out of sync, rename it to “types_.h” and wait for some time. Soon you will get files “Types.h” and “types_.h” in the same dir. Then compare files and delete the one you don’t need. If you deleted “Types.h” wait for files to sync and then rename “types_.h” back to “types.h”
The same is useful for dirs. If you have a dir full of case conflicts. rename “dir” to “dir_” syncthing will pull “dir” and populate it with conflicting files. Then you have to copy contents of “dir” to “_dir” overwriting all files. And after some time rename “_dir” back to “dir”