Muxing to network shares fails every time

Outputting files to network shares is broken. When trying to export a file on a mounted share (accessible through Windows Explorer as a network drive), the job instantly fails with error : --- Errors emitted by job 'Multiplexing to file "output.mkv" in directory "Z:\test"' started on 2023-05-18 11:07:59 +01:00 --- The file 'Z:\test\output.mkv' could not be opened for writing: create_directory() failed. Note that this only happens when the Z:\test directory already exists, as when using a non-existent path the program successfully creates the directory and exports to it.

The drive is a SMBv1 share (I'm unable to use more recent versions as it interferes with other apps), with complete read and write access everywhere on it, by anyone. This was not an issue in v73 and earlier, it only started in v74 and is still there in the latest version, and rolling back to previous versions still works.