Missing Helper "selectFfg" when opening character sheets

[KitCat420]

Describe the bug
After the latest update, character sheets no longer open for the main Gamemaster account of the world. A secondary game master account works fine, however. The issue affects all characters.

To Reproduce
I am unable to reproduce the issue on other world users.

Expected behavior
The character sheet should open.

Screenshots
The console shows the following error:

Desktop (please complete the following information):

• Foundry Version: 12.331
• System Version: 1.905
• Hosted on Forge: No

[wrycu]

Are you running any modules? Have you tried restarting Foundry? The helper is present in the code base of the released version; it not being registered is indicative of an error occurring while trying to register it.

[KitCat420]

No active modules. The console is void of any errors otherwise, and so is the server log. Restarting the server and the browser did both not fix it, unfortunately.