I would say that you should avoid re positioning, it is not that robust right now , secondly after repositioning you have to aply this trick if it works if you are in windows you just try to re-size it will work. 

Second trick is that when you open a complicated process diagram and you see all your arrows getting jumbled up , just close the process diagram   cross button and reopen the arrows will get aligned to what you left last time.

Sanjay Gautam