Hey Clonez,
Since you’ve already tried the suggestion from MrFred, I must ask if you’ve also tried the suggestion from Wittlief? They suggested that you completely remove that material from your project and see if you still receive the error. I’m curious to know if this has been tried yet?
Also, have you tried migrating that specific material to any other project and tried to package it? I’d like to know if it provides you with the same error or not.
Thank you!