Almost every FL Studio project stopped loading after Native Access installed some updates. Using fldiagnostic.exe I was able to narrow down the error to the plugin "Raum v1.3.3". FL hangs when loading if an older version of Raum was used in the FL project. With \Program Files\Image-Line\FL Studio 21\System\Tools\Diagnostics\fldiagnostic.exe you can load your FL projects filtered and deactivate rooms. I hope NI fixed Raum soon.