I have ArcGIS Pro 2.1.2 and concurrent use licenses in two license managers (10.6) in different servers. The problem is that the other license manager lets call it LM01 works just fine but the other LM02 does not work. If I have the LM02 configured it does not let me to change license level or to take some extensions into use. It does not show extensions that I have in the license manager. I can do all that with LM01. If I change the license manager from LM01 to LM02 it gives me an error: Error switching license manager! and Invalid host name.
The only thing I can think of that is different between those two license managers is that there are some licenses borrowed from the LM02.
Other ArcGIS Desktop 10.6 concurrent licenses are working fine from both license managers.