I know that it's not possible to directly import v2.0 preferences to v2.1, but it seems that because I forgot to update that last number, you can't even import from the latest v2.1 to the same version. Damn it, I underestimated the severity of this, I thought only beta testers would notice.
I'll add this in the next version, which will likely be released soon. I'll first wait in case more bugs are found. Anyway, thanks for reporting!