What kind of bug is this?

[BugHunter (Bug Hunter [UEFN])]

They are Fortnite assets since they’re materials linked to the item placers. Running the fix for the errors results in UEFN crashing everytime. I created a post on this with more details:

UEFN Crashes when running Fix-Up on Random Item Placer Validation Errors

I spent 15 hours on my map update, and this was my final step. I wanted to release the map update on Saturday and now I have to wait a whole week minimum to update it.