Issues with highlight in Digital Editions

I have looked at several posts and can't find where there has been a solution. I'm trying to highlight text in Adobe Digital Editions. Sometimes it works, sometimes it doesn't. Other times it is highlighting words a sentence or two before where I wanted it to.

Ctrl M doesn't work. I've tried re-starting and that doesn't always work. In trying to find a solution I've noticed a couple of things.

1. in some cases it is creating a blank 'note' but has not actually highlighted the words (I've found some cases where I have apparently made multiple 'notes' while trying to highlight same section). Going to the 'note' and deleting 'highlight' makes no difference to ability to highlight.

2. Possibly wrong but it seems to dislike highlighting anything in quotes - this includes case references which is tricky when I am trying to study law.

Any suggestions on how to fix this greatly appreciated. 

On image - I was trying to highlight "a Commonwealth statute applies and McNiew would recover"