Incorrect bottom time based on selected gas

 I dive Nitrox 32 or 33%. My bottom time seemed to be appropriate for many dives.  Suddenly, I have exceptionally limited bottom time.  Sometimes it shows up on the computer and app as air, sometimes it shows up trimix.  I have made sure I am setting my computer correctly.  I also checked to make sure my altitude is set appropriately.  Does anyone have any idea what may be going on? I've even tried a factory reset all my setting. Any suggestions are welcome.