Hi Brent,
Thank you for looking into this issue. I thought I understood my own code but having tried to replicate in a simple framework, I find Vassal is preserving the Send Back just right across normal movements, so I must have something getting in the way. At this point, I assume that whatever my code is doing is also stopping the UnDo from restoring my Send Back data. Sorry I didn’t check this one out enough before.
As for v3.3.1-152 specifically, that was a different issue that I spotted. I think it is an issue with either condition &/or trigger handling. I provided a set of demo files in this thread that show different behaviour between v3.3.1 and v.3.3.1-152. I will understand if I need to distill this demo down.