Hi!
Our S, M and L licensing is bound to the performance class of the controller.
The C6017 in the configuration which we officially support has a performance class which fits the S license. The one you use has a higher performance class (has significantly more performance since it has 4 cores). This is why it is treated as M-License. This is intended.
Unfortunately this behaviour was different in the past V5.x versions and we needed to adjust it so that is works as intended. That is why it previously worked with an S license.