Thank you for the quick response and the clear explanation!
I did notice that the "All Items" mod listed ModFixer as a requirement, but I removed the ModFixer.pak file, and it looks like everything is working as intended.
Interestingly, the "All items" mod still doesn't appear within the in-game mod manager list; however, I can tell it's working in existing and new campaigns, so it's not too much of an issue.
