Importing jdb file on SEPM: nothing happens

I have a SEPM server on an air-gapped network. I've been updating it via a LiveUpdate Administrator server which could connect to the Internet, but now that's become unavailable.

When I copy the jdb files according to this guide https://support.symantec.com/en_US/article.TECH102... , nothing happens. I think the permissions are OK. Lots of sem... users have rights.

I've tried both the dark network definitions (which I want) and the normal definitions:

I'm running version 14.0.2415.0200 on the SEPM server. The server has been upgraded from version 12:

I hope someone can help, maybe let me know which logs I could look at.

Thanks,

Marius