To reproduce, execute

/subsystem=jmx:read-resource

Now press the up arrow, to get that command again so you see

/subsystem=jmx:read-resource
The cursor is at the end. Now I want to delete 'jmx' and put in 'ee', so I move the cursor to the ':'. I press backspace to delete the 'x' but the cursor marker jumps back to the end of the line, however when I press backspace again the 'm' gets deleted. This appears to be at the end of the line when I delete the 'j' and enter the 'ee'. So what happens under the hood is fine, but the marker appears to be in the wrong place after it has been moved and editing starts.