I'm actively working on this, but cannot promise anything nor give an ETA.
There's a high chance I will need to (temporarily) remove native support for UPS and only display their website in the app, as I already sunk 3 full work days into it and didn't find a solution.
I'm also re-evaluating their API usage restrictions in hopes that I can use it, but at the very least that would require me to tunnel all UPS requests through my own server and I'm not sure how much it can handle 
Sorry for the inconvenience and wait!