Subsystem to referenced model conversion is disabled

I have a project that requires concurrent execution. Because of this I must use referenced models. My project was working as a collection of subsystems that I wished to convert to referenced models. When I attempted to use the model reference conversion advisor to make the conversion, the ‘Convert’ button is disabled. I was unable to determine why this is the case. What can I check on to determine why this feature is disabled?

[Michael Leiter]

I have the same issue - nothing in the documentation that I can see explains any cases where the "Convert to... -> Referenced Model" in the context menu is greyed out.

I'm using the workaround of just creating the model separately, and copying the subsystem contents into that new model, then dropping a new referenced model block into my parent model, but.... that's all the busy work that feature is supposed to handle!!

[Michael Leiter]

The reason for the issue appeared to be that I had Simulink Test harnesses attached to that subsystem block (possibly having any test harnesses nested in it at all would break it).

Currently Simulink Test has rules against moving a test harness between a normal subsystem and a referenced subsystem block - hopefully there is a good reason for this restriction, even when all the inputs are exactly the same and all buses are non-virtual...