I am talking about Adobe Illustrator 2020, please
Please describe exactly what is in the file and what you did to get to this stage, what the issue is and what you expect to happen instead.
Please show a screenshot of the layers panel with relevant objects selected.
First thing to check is if there is a white rectangle on a layer above the one you are working with.
Second thing may be to see what happens if you hold Ctrl/Cmd and then press X and F and X and F.