To solve this issue, you can try out the following steps,
- Increase input range values of the fuzzy inference system (FIS).
- Limit input values to individual input range values before you feed it to the FIS.
- Make sure the rules cover all the input space so that at least one rule is fired during the inference process. Look at the control surface of the FIS.
- In evalfisOptions object, set diagnostic messages to "none".
If the issue is not solved please share your model to reproduce the issue,
Hope this helps!