If the template is remote from the document, that could cause it. Glad you are not experiencing it now, though.

I generally advise storing both Workgroup Templates and Add-Ins (global templates) locally with updates upon login rather than using them from a central location. This is one of the reasons.

If you can, I would save that macro-free .dotm template as a .dotx template. Unless the template needs to have macros, I always store my building blocks in .dotx files. It is cleaner and who knows what security MS or someone else is going to use to block .dotm files in the future.

.dotx Building Blocks holder templates can also be stored in the Building Blocks folder. I know of little reason to do so, though, since that folder location can be harder to figure out than the location of the Startup folder. (At least it is harder for me using vba or to explain to someone remotely.)