Marlin mid-print controls give strange error

I've mostly printed from USB so havn't noticed this till recently, but when I print from SD and try to change the parameters mid-print (eg hot end temps, heated bed) it just goes comes up with the edit screen for flow, and then won't go back to the previous screen. It is not frozen and I can edit flow, but clicking the dial will not go back. Everything works fine if i'm not running a print

Im using ramps 1.4 with a reprapdiscount LCD. Anyone else had a similar problem?

I've tried editing the flow mid-print, set it to 99 and the flow stopped completely.

Also, if you choose "stop" from the menu mid-print, the printer will stop for a second, then go on to do a spectacular head crash, dragging the nozzle hard across the bed.

This was on the very latest RCBugfix download as of a couple of weeks ago.

For this, and other reasons, I've moved to Repetier...

I started with repetier and found it worse for bugs to be honest.... Might be worth going back now I know more, especially since I used to use the online editor rather then just edit it via arduino software