Make freeze top row work consistently when filters are also used. Has been an issue for many versions.
Freeze Top Row, when combined with filters often leads to unexpected behavior. Today, the first row is not freezing on my sheet when I have filters enabled. There are also issues with cells not accepting focus (or at least displaying that focus has been accepted).
Have you considered using a Table for your data so you don't need to use "Freeze top row" anyway because the table headings and filters are shown instead of ABCD when you scroll down?