i get this error occasionally… i just experienced it these days back… here was my fix: I went into the struct, opened it, saved it, closed it… went into the file that was using that struct (in my case just a save file, even though it is referenced by many other bp’s just going into the original save file that struct is saved in fixes this bug)… so open that save file, click on the struct variable, compile the save file, close it… boom project now builds successfully… its not the first time it happened to me nor will it probably be the last… it is weird but these fixes work…