The units are pulled off the ‘current state’ of the device attribute. When the device is first sync’ed over, the system copies the states over 1:1. After that, it relies on events and I suspect that there’s something quirky with the next-gen SmartThings events. I’ll take a closer look.
As a workaround, you could use a Super Tile to build a custom layout. It probably wouldn’t make sense for lots of individual devices as you’d have to create a Super Tile for each, but it could be a good use case for combining several of the devices together into a single Super Tile.
Edit: this is fixed with the October Updates 