2021 "Could not use the brush tool because video layers are only available in Adobe Photoshop 2021"

Hi,

Earlier today I was using photoshop to rotoscope and it was working fine--I had no problems creating video layers or drawing on them. But now, later the same day, when I try to use the brush tool I recieve a pop up that reads: "Could not use the brush tool because video layers are only available in Adobe Photoshop 2021" even though I am using the newest 2021 version. Does anyone have any insight as to why this error might be happening and what I can do to fix it? I'm working on a deadline so a quick response would be appreciated.