I don't remember ever hearing of an issue like that. Is there any chance the template was saved with SW2016 at some point? On the other hand, if it was I wouldn't expect SW2015 to be able to open it all. The only thing I can think of to suggest would be to open an existing drawing with SW2015, delete all drawing views and annotations that don't belong to the sheet formats, and save as drawing template. Now when using this template with SW2015 both sheets should be there.
What's the difference between a sheet format and drawing template? and Why aren't the changes I made at Tools > Options > Document Properties saved when I start a new Part? may be of some help if you're unfamiliar with any of this.