My MAX GB Storage is +/- @ 494gb. I Deleted 11gb. Used FCP for a 105.9Megabyte Vid and My Available Storage is at MAX?

DANGER!

Forget FCP for a second.

You are risking crashes and loss of data by using your mac with such a full drive.

It is always recommended to have at least 15%, preferably 20% free on any system drive.

20GB out of 500GB is 4%. It is not even enough for the basic work of your OS.

I second what Luis is saying. I've had it happen to me, I've seen it happen in both Mac and Windows computers many times over my career. Also, get the app "Arctic" to delete all the render and analysis files in all of your Libraries. Then get a fast secondary drive and move stuff to it, ASAP!

When a drive gets below 15% free space, all sorts of odd, almost inexplainable symptoms will begin popping up. Drives on any OS need that space to write, store, and read temporary working files. If they can't do that, mistakes get made in the CPU's processing, and you risk serious data loose, as Luis said.

Dead serious, clear off that drive ASAP or you will (not might) be in serious trouble.

Switch off background rendering and leave it off. The system is constantly generating files. How big are you drives and how much free space do you have?

You need to maintain at least 15% fee space on your drives. This drive is so full out is likely to fail.

Did you empty the trash?

Until you empty it the files remain on your computer.