Just a note - I did retest on SU12 (1.31.22.0) the issue is still present so please do not close it until it really gets fixed.
Some other important gliding related issues were prematurely closed without proper fixes - like DG-1001 tail wheel provides no lateral stabilisation on ground, glider "dances" on ground and Too small distances between thermals suitable for gliding which both are far from fixed and closing them prevents further feedback.