I got an email response from Uros. A firmware fix is in the works. Within the next week actually. Excellent!

Thinking the worse last weekend (no fix for months), I decided to start hooking up the SC cable from the vario to a separate momentary switch as a temporary solution. It worked fine when the "auto SC" feature was turned off. However, when set to auto-sc (e.g. GPS), the switch did not appear to work anymore. I thought that this sc line would still work and override any auto-sc logic running. The "vario priority" input also appeared to stop working as well. I ran out of daylight so I didn't do as much exhaustive testing as I had planned. I'll report back my findings by next weekend.