Sounds like you could have a cloud save problem? SU4 introduces a popup to indicate that their cloud saving is corrupted have you had that Cloud save error (error code:1047... and now 2047).
On a reload of the sim does it also revert to an older selected plane, no matter what you flew last?
AFAIK the hobbs is a pretty basic instrument in all planes, relying on the underlying sims state save abilities.