I encountered the same issue in UE5.6.
In my case, adding a Scratch Pad Module to the Simulation Stage that was causing the issue eliminated the error. Disabling this module does not cause the issue to occur, but deleting it causes the issue to reappear.
Alternatively, setting the Execute Behavior to “Not on Simulation Reset” may also resolve the issue. In this case, no additional modules are required.
I am not sure why this behavior occurs, but I hope this information is helpful to those who need to address this issue.