RA has a Tech note that lists several possible causes and solutions.
https://rockwellautomation.custhelp....US#__highlight
Deleting the harmony files was #1 on that list.
I would check the RSLinx Classic service in the Windows Services. Stop it and make sure it is set for Manual.
They also suggest checking the Harmony service and making sure it is running. I would stop it and the RSLinx Classic services together and make sure they are both set for Manual. hen when you open RSLinx they should both be running
The other possible issues are a bit more severe to fix. Corrupt EDS system. Activation issues.
OG