Thanks to @JediHoplo in another thread about this, I was reminded to check on the software update status on my mobile phone.
I now feel creepy that it had been sitting in an error state with the last update having failed back in March, but oh well. After successfully updating, it syncs to Fit just fine once again.
I’m still not sure why an update failure in March would cause a sync failure near the end of April, but whatever, I guess.
Somehow, I just noticed a few days ago that it stopped syncing data to Google Fit last month, on the 24th of April or so.
As someone who is usually the one to assist others with this kind of stuff in my life, I have tried everything I can think of to troubleshoot, and even though it’s obviously still configured properly (the same configuration that it was working properly with for months since I got it last fall), it just won’t sync to Fit.
Any idea what’s going on here?