Renames changing only the casing on case-insensitive file systems on Linux (e.g. ext4 case insensitive or FAT32) are not applied. This seems to be a general issue on Linux when dealing with case insensitive files. I also could not change the casing with Nautilus or on console with mv (the latter will actually fail as both paths refer to the same file).
Needs a workaround like double renaming the file to a temporary name and back.
For SMB shares on Linux there is a similar issue
PICARD-1986 , but the root cause and fix is slightly different.