I was working on another project and tried something that I thought always worked and it didn’t.
When you drag a cell with a number with the Fill Handle it copies.
When you drag a cell with a number but hold the Ctrl key down it increments.
Well the Ctrl key didn’t work when I had a filter in place in a separate part of the sheet.
Has that always been the case? I have never seen the Ctrl key not work with the Fill Handle.
Also the increment worked across columns but the little menu that displays only had one option.
WEIRD!!
I did a short video of the problem see it below.