Hello Friedrich
I also had this happen to me yesterday (30 November 2021). Nothing changed that I am aware of, except of course possible updates to AV and Windows.
I have been on 2019.7 for a while and have successfully done code-signing with it for numerous installs, most recently 24 November or so.
I checked that signtool.exe is new (downloaded the SDK from MS) and reinstalled capicom.dll from your installer, as per previous threads on the forum.
I disabled the AV but this did not change anything.
I can successfully code sign files manually with signtool.exe, using what I imagine would be the parameters SB uses, with or without a time server. This happens with AV on and off.
The only other possibly useful thing I can say is that the failure is pretty quick: From the time the code-signing starts to failure is instantaneous - it looks like it is not even "trying" if this makes sense to you.
Fortunately not a show stopper but it is tedious to do the code signing manually, and I have to leave the archive integrity check off - the manual signing breaks this check, which kind of makes sense.
Regards
Daan Marais