I was having the same problem. I scrubbed the plate with Isopropyl Alcohol and it still wasn’t sticking. It turned out that my first layer was printing too fast on the file I was printing from (the Benchy file that came on the SD card with the printer) and the other file I was testing with was printing the first layer too high. Another maker suggested printing a calibration cube and it printed perfect. I ended up buying another PEI plate just to have a second that I could rotate out. We also were suspecting the weather change. It had warmed up the week I was having adhesion issues and I still think some moisture got into my filament. I have seen others suggest “baking” filament, though I have yet to actually do it. My problem fixed itself before I had got to that step, though if it were to happen again, “baking” would likely be my first step in troubleshooting. So there’s a few things to look out for : Layer speed, Layer height, and moisture in filament. I would also try the calibration cube as your test print.
If you wanna check out the thread it’s here Best of luck and hope this helps