first of all it would be helpfull to know what errors the jump commands give you. next, have you looked up the error head in the “Dobot Magician ALARM”-PDF? althought its not that well written it helped me to find out some errors i already got. most commen is the error when you want to move the dobot arm outside of its workspace.
here the link where you can find that alarm-pdf-file in case you dont have it.
another reason i could imagine is the “jump-parameter”. Jump moves are supposed to move up, before moving to the given point. the moving height from the Z axes is given through the “jump parameter”. there are also some other details you can set. like the height the Z axe should move in a jump parameter, the max. height the Z should be in any case, …
maybe some of those parameters are too high for the dobot arm.
and yes, the support from dobot dropped pretty hard. i once read somewhere their online supporter left the company. althought this isnt an excuse it might be the reason why the support got so inactive.
any way, i hope i could help.