Mine also shows temperatures below -1.
It displays above-zero temperatures all the way down to 0 OK.
Then there's a gap between 0 and -1.
Then below -1 it's OK again.
So, when the temperature drops, it goes directly from 0 to -1, whithout displaying anything inbetween.
This has gone unnoticed for years, until a few days ago, when I started plotting temperature graphs.
There seems to be a rounding error right where the polarity changes.
Are you sure your 1216E can display for instance -0.5? Up that far north you may have to wait a few months to verify this...
(And are 1.07 and "01.01" the same?)
73,
Jonas/SM5PHU