Configure Custom Skills not working

[AritheZoo]

I just updated to v13 of Foundry as well as the latest version of the 4E system. Under Configure Settings the Configure Custom Skills button does not function.

[FoxLee]

I'm unable to reproduce this error locally; the form opens as expected and I can successfully configure custom skills that show up as expected on actors. Is it still an issue with all modules deactivated and/or in a freshly-created world? Are you able to see any error messages in the developer console (f12)?

[AritheZoo]

This is the error message:
Uncaught (in promise) TypeError: this[#customSkills].map is not a function
[Detected 1 package: system:dnd4e(0.7.9.1)]
at new CustomSkillConfig (custom-skill-config.js:11:42)
at #onOpenSubmenu (foundry.mjs:68126:17)
at #onClickAction (foundry.mjs:28185:56)
at #onClick (foundry.mjs:28138:51)

When I deactivated all the modules it still did not work. I got an almost identical error message:

Uncaught (in promise) TypeError: this[#customSkills].map is not a function
at new CustomSkillConfig (custom-skill-config.js:11:42)
at #onOpenSubmenu (foundry.mjs:68126:17)
at #onClickAction (foundry.mjs:28185:56)
at #onClick (foundry.mjs:28138:51)

It works on a freshly-created world.

[drywallmud]

I have a similar issue with skills on the NPC sheet, the checkbox circle is unresponsive as I attempt to cycle through skills training in PC-style baseline values mode on Fox's 4e Styled NPC sheet.

If I switch to the core sheets, skills is sometimes not there at all, but when it is, I can cycle through. May or may not be related?

The core sheets skills disappearing:

[FoxLee]

I have a similar issue with skills on the NPC sheet, the checkbox circle is unresponsive as I attempt to cycle through skills training in PC-style baseline values mode on Fox's 4e Styled NPC sheet.

If I switch to the core sheets, skills is sometimes not there at all, but when it is, I can cycle through. May or may not be related?

I suspect this is a separate issue, and probably related specifically to my module. Unless the disappearing skills also happens on monsters that have never been set to my core sheet? If it only happens when you've been on my core sheet and then moved to the system sheet, I imagine that's where the problem lies.