Oh, yes. Of course. It slipped my mind that all mined coins are sent to separate addresses in the wallet.dat So getting the privatekey for the main wallet address won't actually move the coins. Ha, my bad. If you can reply to my private message we can try and fix your problem.
That's what I was thinking too...
edit: I finally solved the problem.
To explain shortly: I, by mistake, imported the privatekey of a receive address (since the account didn't really have an address since it was used only for solo mining).
Then I ended with this address in both the old and new wallet (which were using the same blockchain on the same computer)
So I sent to that address the coins on my old account (which showed up on the old wallet as a 0 ROH transfer to myself)
I went back to the new wallet (having also that address) and after a little while these coins appeared in the new wallet...
I'm glad you got that fixed.