For testing only. MEMlib seems to have issues.
I ran it for few days but it got stuck on a certain block number.
From the log file: "No valid safeboxes/blocks found from other peers"
I had to revert back to v5.3. That one still works.
To summarise. I had to wipe the DATA directory completely and let the wallet rebuild the blockchain.
Thanks for reporting.
Yes, current "alpha" version is not still stable. Working on a new "beta" version fixing some detected bugs.