Fenix 5 Altimeter issue...

The Altimeter on my Fenix 5 has stopped working randomly.  When I auto-calibrate, it shows the correct elevation but when I go for runs it doesn’t record any elevation changes at all.  It worked perfectly prior to about a month ago.  At first signs of an issue, it was recording drastic elevation gains like 40K+ gains, now it doesn’t record anything.  I cleaned the sensor and recalibrated, etc. to no avail.  Any ideas on what the issue could be other than just a failed sensor?