I see that the Fcn block highlighted in yellow (giving the error message) is part of a closed-loop, where in order to get a result it needs to have all those input values, but some of those inputs depend on the output of the block. Try to run the model step by step via Debug mode.
Another point: The Fcn block is not longer recommended. See more about it here:
If possible try to use a MATLAB function block instead.
