Physical modeler error reading plates

I changed some member properties and point loads in an existing STAAD project built using the physical modeler. I then clicked "Analytical Modeling" button and switched to the analytical model. There I built in design parameters and commands. Then I ran the analysis to make sure I had no failing members. Switching back to the physical modeler seems to cause no problems and everything looks correct. But when I then try to return to the analytical model, it gets to about 50% when the "Error during Analytical Model Creation" pop up window appears. The details of this error says: Guid should contain 32 digits with 4 dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx).

I don't understand what is happening and it makes me question the results that I was able to obtain. 

Please help.