Sorry, I can't think of any reason why code that works in a customised question wouldn't work in the prototype. Unless the various sandbox limits (memorylimit, cpulimitsecs, numprocs, ...) are somehow different in the two questions? I'd suggest setting memorylimit to 0 (meaning no limit) and raising numprocs to some ridiculously large number like 500, just to check if that's where the problem lies. Beyond that I'm afraid you'll have to resort to more serious debugging techniques.
As a last resort, setting the sandbox debugging mode should result in the entire run being saved in /home/jobe/runs, and you can then explore what's going wrong in the run, assuming you have admin level access to the Jobe server. To set that mode, enter
{"debug": 1}
as the sandbox parameters under advanced customisation.