Incorrect usage report Resmed Airsense 11

[hydra]

I've been using the Resmed Airsense 11 for about a month. The reports on the app were reporting correctly up until a couple nights ago.  Now, even though the machine itself gives the correct usage report for "time used,"  the MyAir app shows a much lover number.  For example, last night, the machine recoded the correct usage of 7:38 minutes.  But the MyAir app shows a usage of only 3:40.  

Any ideas why this is happening and what to do about it?