what I am doing may be original language and geek, but it should be simple and is intermittent and failing:
I am working in the Mounce Workbook, and want to highlight verbs to parse.
I double click the verb, it highlights and the ANLEX opens as I expect.
I have a shortcut set the letter "Y" set to yellow highlighter marker.
The Greek verb is highlighted in the workbook text. sometimes when I press the Y on my keyboard, it will marker-highlight, most times it doesn't. even if I have the highlighter tools up, and click the yellow highlighter - the Greek verb in the text that I have highlighted with the mouse/cursor - doesn't yellow highlight.

the "αἴρων" won't highlight yellow (and others in the workbook - this is just an example, you can see others that are highlighted yellow) - in fact - I can no longer highlight yellow anything after the first few that I did there in the image. 