This has been an annoyance since I got a 4K screen. This is windows 10, VMSP 17.0 trial. it does the same with 16.0 platinum. This custom template context box is always way too big if you scale your screen. You have to mess with auto-hiding task bar to be able to use it, and even then sometimes it is impossible as seen in video below.
I imagine it would be fine if you did not scale screen, but you have to sometimes or text is tiny and unreadable.
If they are going to auto-size boxes so close to screen resolution they better get it right or let you resize them. I have to go in and mess around with custom scaling for the entirety of windows to make this close to usable and it is still to big.
Do they take feedback from customers? There are some other really bad usability problems that never seem to get fixed or adjusted in this editor.