Are you able to obtain another similar design template that may not yield this kind of behavior? Or, is recreating the template an option?

Since this type of corruption is so subtle (that is, not the kind that prohibits you from opening the file), I'm not so sure how helpful the below actions will be with fixing what is wrong with the design template...

https://social.technet.microsoft.com...iceitprolegacy
Unfortunately, there is no Open and Repair function in Powerpoint like there is with Word...