Dear Sam Focer
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Based on your description, it seems that in SlideShow mode, the hyperlinks work with mouse click but not touch screen, but if start the slide show, the hyperlink can work well with the touch screen overlay.
If my understanding is correct, please go to PowerPoint web version in the browser to check if the same behavior will happen again.
If this behavior didn't happen in PowerPoint for web, maybe this problem is related to the PowerPoint desktop app. Thus, we would like you to check whether the behavior is related to your user profile. In this situation, we suggest you creating a new user profile on Mac on your Mac and see if any improvement. It is worth trying because it will help you narrow down whether the issue is caused by a specific corrupted user profile.
Looking forward to your reply, please notice the above information is vital for us to further assist you, any updates please feel free to post back.
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Sincerely,
Stacey | Microsoft Community Moderator