Same issue. I am on Steam as well.Mine was working fine till the latest version. I have read the release notes, and changed the install path but no still getting 0 Liveries.
Also, I cannot set Light GA or AIG etc on the PSX app. Ticking the boxes does nothing. By default, PSX sets my default path to users/appdata/roaming MSFS/packages. That is not my install path. I changed it to G:\steamapps\common\MicrosoftFlightSimulator but still get zero liveries.
Edit: Why is PSX searching here ? Community path: G:\SteamLibrary\steamapps\common\MicrosoftFlightSimulator\Packages\Community
Scanning for liveries ...
G:\SteamLibrary\steamapps\common\MicrosoftFlightSimulator\Packages\Community does not exist, skipped!
No liveries found!
Path should be G:\SteamLibrary\steamapps\common\MicrosoftFlightSimulator\Community ( Default path for Steam )
Have reverted to previous version in the mean time.