Solution do resolve the issue:
Get the newest version of Dash 0.13.2
Because you have pre 13.x version you must reindex the blockchain in order to start your dashcore wallet.
To do this edit your dash.conf file and add this line: reindex-chainstate=1
Start your wallet.
Let it sync.
After it is fully synced stop the wallet and remove the added line from above.
Save and erstart again.
Solution succesfully applicated, wallet works, mining amounts appear on the wallet ;)
Bitmain mining -> payment history -> amount paid. It is the fifth day when bitmain says amount is paid, but the wallen can't see the payments.
The system says "not yet redeemed". But I'm not sure it is connected with the problem.
Windows Win32 wallet 0.12.2.1. Win64 wallet 0.12.2.1.