Yeah, I actually opened a DTS case for this and while it hasn't been updated in awhile, I basically got the vibe that there wasn't totally complete API support for what I wanted to do.

This is not currently supported by TabView. I'd suggest you file a feedback asking for this functionality. If you really do need this, you'd need to implement it yourself, perhaps by custom wrapping UITabBarController but that'll be a bit of work depending on how many features you need.

Since I wrote the above post, I've been trying to get it to work with the focus system and it feels like I'm so close, just can't quite get it there. If anyone has any tips, they would be much appreciated.

Hmmm. Should I be using the Focus System for this?

Odd. Yes, works for me with their sample and in my own project.

I had this happen with Google Sheets but only that once so I haven't yet filed a FB.

This really sounds like a bug - I’d encourage you to submit a Feedback with the above sample code - limited time to get bugs fixed in this release cycle!

Seeing the same thing here. I'll dupe your FB.