760Li sliding sunroof cover issue

The sliding sunroof cover (sunshade?) on the ceiling of my 2003 760Li suddenly stopped cracking open a couple of inches when I press the sunroof button straight up. Pressing that button props up the back of the sunroof, and normally, would cause the sunroof cover to crack open a couple of inches.

The sunroof pops up in the back, but the sliding cover stays closed. Could be a problem if you forgot you opened it and it starts raining.

I already did the basic sunroof re-set, holding the button upwards for about a minute, while it re-sets itself. That reset did not fix the issue. Searching for basic terms like "sunroof problem" or "moonroof problem" are not turning up with this issue.

Any clues?