There could be a few reasons for this
- Its possible some of the model blocks are not supported by SLDV, in which constraints will not be generated.
The MathWorks documentation provides a comprehensive list of supported and unsupported blocks for Simulink Design Verifier. You can find the full list in the SLDV documentation: https://www.mathworks.com/help/sldv/unsupported-simulink-constructs.html
2. Also you may recheck the configuration settings as certain parameters have to enabled for constraints to be generated.
3. Model authenticity also needs to be validated, for a problematic model such as having syntax errors or being incomplete, the test cases generated may not provide sufficient info to create new constraints.
