Paul, of first of all you're awesome, I've watched and applied like 2347239480 of your videos!
I did have uniform text scaling checked. Unchecked it does stop the heading from shifting dramatically in size, it stays the same. I am wondering overall in my project if I am going to see a lot of wonky looking text. What is your experience in using or not using scaling? My project has to me 100% responsive, they are very interested in all views looking good, small screen portrait AND landscape.
Enable Uniform Text Scaling does one thing. It ensures that any two objects on your slide that are the same font size will retain that relationship with one another across all the various devices you might be viewing a responsive course on. This is great for objects like buttons that should have a consistent design with one another. It isn't so great when the two items have nothing to do with one another.
The solution may not be to uncheck the Enable Uniform Text Scaling but rather to ensure that each item has it's own unique font size when it doesn't relate to other objects on that slide. For example, keep your button fonts the same size but make sure that headings don't use the same font size as other text objects on the page.