After upgrading to Nextcloud version 10 from 9, creating and syncing files and folders with special characters (space, áéűú etc.) not possible. On version 9 this was not a problem.
Server configuration is Apache 2.4 with ProxyPassMatch to PHP-FPM 5.6.26.
It seems to be working for me. Do you have a specific test case other than, 'áéűú '. Are there any errors in the nextcloud.log file, or the sync client?
I see only this error in apache log:
[proxy_fcgi:error] [pid 21287] [client xxxx:7976] Invalid status line from script ‘K%C3%A9pek’: 0
Opening a previously created directory in version 9, is allso not possible!
I had the same issue, please look at Unable to access directories starting with a hash sign and check if this also applies to your configuration.
I had same issue with space in folder name and your link solved the issue for me too (apache2 + fcgi and use FilesMatch instead of ProxyPassMatch).