I just got above "error", no more.

And of course I just updated to 0.9.3 before testing!

--edit
Just one more thing:
not obviously told, but to me I have checked standard page as well as battery and cell search pages.

--editedit
And another possible error popped up. But this one I have also seen earlier.
When selecting battery page, the values are shown (which seem to make sense according to bnf/bq27).
But the window sometimes closes on its own and vanishes. Restarting netmon and selecting again shows values and stays open (not always, but most often).