As I had a normal, OC and air only dive yesterday, I was coming back from the abyss with approximately 35mn of deco time and checked the decoplan on my ostc. No problem so long. Exit from decoplan, still OK. But suddenly, as I was not moving, the % of my GF became terrible: 110%, 150%, 250% and so on. I was at 9m or so, but my ostc send me back to 18 or 21m, with 30 or 40mn of deco time, and more than 99mn of total time. Beep beep during the rest of my dive. The gauge and timer were still OK. Back to the ship, the dive and datas on my logbook were strangely pretty ok...
Attached a screen capture of my dive, where you can see the big red alert since 33rd mn onwards. Tell me if I can send you more informations for debugging.

Regards
Olivier
OSTC v. 1.29, OC with GF (default).