Variant Manager Function Blueprint Invalid Class

Good day.
I have created a Variant Manager with several variants.
For some of my variants I used the “Add function Caller” and created custom functions for them.

The functions worked fine for a while and then I started getting the following error when I try to open the function to edit it:

“Blueprint could not be loaded because it derives from an invalid class. Check to make sure the parent class for this blueprint hasn’t been removed! Do you want to continue (it can crash the editor)?”

I can now no longer open or create any functions and when I activate a variant with a function, the editor crashes.

I was able to recreate this error in a new variant manager by moving the manager file from one folder to another.

I hope someone gets to answer this. I am not too good on this.