Simulink design verifier doesn't finish test case generation

I am currently using simulink design verifier to generate test cases. When I use it to extend testcases using existing tests, the tool just gives up after about one hour, despite my max run time, which is set to 300000 seconds. The tool gives no additional test cases other than existing test cases.

Is there a reason for this behavior?

[Angela]

Did you check model compatibility before generating test cases?

https://www.mathworks.com/help/sldv/ug/check-model-compatibility.html#bt8zwoq

[Pat Canny]

I recommend contacting MathWorks Technical Support. This question requires more information.