When I logged in this morning after just over 8 hours from the last time I looked at my Idle game (I have 10 hours of idle time), no time had passed. I had 6 hospitals upgrading when I left and all 6 were still upgrading when I returned. Also had no noticeable progress smelting, crafting, or generating troops or money.

Not a big deal as this is the first time it has happened that I know of, but also not expected behavior.

Did you manually sync and properly close the app before going to bed?

It appears that your nightly progress was overwriten by an old save.

I think I did. I am pretty careful about syncing before I make changes (i.e. adds on phone vs. browser)

Just notices:

Started this level: 1 day ago
Session age: 16 hours

I did not use any time warps, not receive any from "doors"

This aligns to losing 8 hrs.

Started this level: 1 day ago = 24 hrs
Session age: 16 hours = 24 hrs since start - 8 lost hours

Perhaps the Sync failed?

Though even still this doesn't make sense, if you have 10 hours Idle time, and only left for 8 hrs ... can't explain this.

if the sync failed, the hospitals wouldn't be upgrading, right? The statement: "My hospitals were still upgrading" suggests that these upgrades started right around the time, that the idle time should have started. So, if they still upgrade, then clearly (almost) no game time has passed since starting the upgrade, and based on the fact that they are still upgrading shows that the upgrades happened before the last sync (unless you have auto-upgrading for hospitals, then my argument might be inaccurate). So, this to me seems to be a clear bug (of some sorts) that is worth reporting.

Yeah, deff report this as a bug, even if it was "just" a problem with the sync, cause it should auto sync on closing

(Menu > Help > Contact > Report bug)