I've solved this. I believe the root cause is a small bug in the Parameter Estimation GUI.
However, what's more important to note is that I had originally overlooked a very powerful feature of the tool - the capability to generate a baseline script to execute the same cost configuration as the GUI.
I suppose I should've expected no less of a capability...
When executed from the command line, I can see that the same experiment actually terminates without errors and produces a feasible solution. For whatever reason the GUI bugs when all these particular planets align and the optimality tolerance is violated, and it just chooses to restart the simulation and throw the error.
In summary, if you're exploring sdo or parameter estimation for the first time, don't overlook the aforementioned hyperlinked capability.