Maybe it is a bug in DateTimeUtils.cs

[scegg]

https://github.com/PKISolutions/Asn1DerParser.NET/blob/master/Asn1Parser/Utils/DateTimeUtils.cs

line 21-22:
I think your + - is set oppositely.

[scegg]

https://en.wikipedia.org/wiki/ISO_8601

[Crypt32]

Indeed, it was a bug.