There is a thread relating exactly to this problem. I know. I started it. But the solution seems to be, look at the upper right hand corner for a CO2 and/or battery icon. When your ready to surface and those icons are displayed click on the CO2 icon first. If just the battery icon is displayed, then click on that icon. Either one of those should solve your CO2 problem. I guess this is a known bug. But see if you can located those other threads if you need more help.
Godd luck.
