algorithmic modeling for Rhino
Please make sure you have the latest version (2.55), this will fix your problem in this case.
And of course when you update to the latest version you need to rerun the simulation.
Also one side note: make sure to flatten the number parameters holding your objectives before inputting them to WallaceiX.
I have the same issue. I do use the latest version 2.55, yet I come across this issue on every optimization. But, I did not make my objective's numeric parameter as flatten. I will do it and check again.
That should fix your problem. Let me know if the problem persists, and if so please share your file so I can take a look at your problem.