I was facing a similiar issue when simulating my model containing S-functions. A workaround for me was to turn off the Save final operating point setting in the Data Import/Export section in the Configuration Parameters.
If saving the simulation state is necessary for your workflow, some changes can be made to the S-function to accomodate this functionality. The following documentation suggests how to achieve this using the "GetOperatingPoint" and "SetOperatingPoint" functions, along with an example:
Pwork (or Pointer work) vectors store pointers to data structures, serving as interfaces between S-functions and other applications. More information can be found in the following documentation:
Hope this helps!
