Here we are 5 months later and the problem still exists with the only semi-official response in this thread being from a beta tester telling people to stop whining about it (in essence). I've got 7 Veras and 30+ thermostats under control of custom software that programs them via the XML interface in conjunction with a COTS scheduling package. UI6 totally screwed things up. I'm just glad that the users here are giving workarounds, because the response from MCV has been lots of crickets in this thread.
Yes. Roll back to UI5 per the helpful instructions in this thread (not provided by MCV, you'll notice). I'm really sorry I've glued us into this product. The search is now on for a company with better product support and customer service. I'll most assuredly be migrating to another company as soon as reasonably possible.