I was only able to solve the error by deleting all references to the struct in the blueprint and the struct itself. You could obviously create a new struct, just make sure not to move the struct or rename it as jayice said.
If you don’t want to risk having your project break again, you could use a class instead, as you would do in regular programming. (You sacrifice some performance though)
It would be nice, if Epic fixed this bug as soon as possibly.