Hi Ben, I do not know why you are seeing this. However, I will tell you what I would do to track down a problem like this. I would follow the instructions in the developers getting started guide found here: https://github.com/xtuml/bridgepoint/blob/master/doc-bridgepoint/process/Developer%20Getting%20Started%20Guide.md
That allows you to debug and make changes to BridgePoint!
After getting a good build I would then launch the tool in a debug session. I would then set a breakpoint perhaps on the line called out by your call stack here: “at org.xtuml.bp.core.Vm_c.Execute(Vm_c.java:469)”
I would then execute the procedure to reproduce the problem, hit the breakpoint and go from there to see why it happened.