macos struggles even with itself about filename case-sensitivity:
$ mv file.txt FILE.TXT mv: 'file.txt' and 'FILE.TXT' are the same file
this means when one does
mv file.txt a ; mv a FILE.TXT on one computer, syncthing breaks even across (case-insensitive) macos machines. I think one then needs to hunt and hand-fix files.
I am guessing that the problem here is that the macos
rename file command gives an error, which in turn gives a syncthing error. however, this should be relatively uncontroversial to fix, i.e., without implications for sync-ing to case-sensitive computers. it would merely require testing if
lc() is the same, and if it is, to rename through an intermediate tmp file.