Hi,
You could try using the "nue" option of the $fermi keyword:
$fermi tmstrt=300 tmend=20 tmfac=0.95 hlcrt=1.0E-01 stop=1.0E-03 nue=2
Here is the section from the manual:
The optional nue value (number of unpaired electrons) can be used to force a certain multiplicity in case of an unrestricted calculation. nue=0 is for singlet, nue=1 for dublet, etc.
I think you can avoid using closedshell shift and stick with the automatic shift.
Best,
Antti