You are correct, layers always start at frame 1.
You need to have a layer with the first drawing blank and 39 clones after it. Then you can have your cycle from 40 to 55. Shift select your cycle (drawing 40-55) and copy/paste it below as many times as you need it. These copies are clones too, so cycling doesn’t take up memory and all drawings are properly linked.
I do appreciate that in your case you could have saved a step or two if this was done in another way. But I think designing the software how I did keeps the simplicity greater in general.
(I can’t run away from remembering your point though. 😉 Maybe I’ll do something about it at some point.)