Sporadically unable to type into a text box in PowerPoint

PowerPoint for Mac version 15.17 (151206)

MacBook Pro

Is anyone else having this problem? I have numerous PPT files where I sporadically cannot edit in a text box. I click inside the text box, try to start typing, and get the "ding" sound that says nope can't do that here. Paging up and/or down several times solves the problem, but the issue is so pervasive that it's becoming a huge time suck. 

The issue occurs on both newly inserted slides, as well as existing slides. In addition, I could just have edited a box, paged down (or into another app) to look at sometime else, come back to that same box, and wham, can't edit it. 

In addition, I can click in a text box, hit return to get a new line, and then WHAM, not be able to continue typing.

Most (all?) of the PPTs that I am working were created from the same master template. Some of the files where created on Office 2011 for Mac (by me). Others were created by co-workers who are running Office 365 on Windows (primarily Win 7, maybe some Win 10).

I've had this happen in multiple files. Example frequency is 30-40 times in a 3 hour time period (working in PPT the entire time).

In addition, I've now run into the problem where objects copied from one slide to another in the same PPT are not editable at all. I am unable to move them, resize them, or do anything with them other than delete them. I have not been able to determine how frequently this additional problem occurs. It seems rather like a variant of the text box problem.

I haven't explored whether this happens using files created using other master templates, so I am not sure if it is a problem with this particular template or not. If it is a problem with the template, it's still got to be a bug... Can't imagine how I would fix it on my own, other than continuing the cumbersome workaround.

Thanks!