GarageBand project corruption after applying 'Sweet Cream Synth Lead' from Soulection pack

Whenever I apply an effect called 'Sweet Cream Synth Lead' (from the Soulection pack) to any of my tracks in any project, after I close the project and try to reopen it, the program refuses to open the project. It says I need to update to the latest version of GarageBand.

I do have the latest version of both the Apple software and GarageBand.

This happens across all platforms (iPhone, Mac, iPad).

Resetting GarageBand doesn’t work.

Trying to open the project in Logic Pro doesn’t help.

Reinstalling the Soulection pack doesn’t solve the issue either. Please help! Thanks

[Re-Titled by Moderator]