Hey. I tried migrating the blueprint to another project and it still happens in that one.
I can send you the project I guess that would help you more than me guessing what it caused since I actually have no idea how to reproduce this. It just happened all of the sudden…The only thing that we did was adding a new S Item Data variable.
To reproduce what happens to me:
Go to Content → Blueprint → Interaction → BPI_Parent
Open it, it should throw an error which you see above.
Then compile it and then save. Then reopen the project.
The error will still persist.
Here is the project:
https://we.tl/u1NOn7j7Br