From time to time I am getting this error, when I try to save a step file as an assembly. Often I receive the step files from clients, and when I open the file and wants to save it, I get this error. The only solution that seems to work is to just continue clicking OK.
However, when you have to do that about 100 times, it becomes really tedious.

Why am I getting this error? My templates are working just fine, except for cases like this - obviously.

Thanks in advance.