Freeform Gradient Disappearing

That sounds like a recurring Illustrator issue rather than something you’re doing wrong. Since you’ve already restarted everything and tested CPU/GPU, I’d try saving the file locally as a copy and reopening it. Interestingly, another recent Illustrator user reported the same Freeform Gradient disappearing issue and said this fixed it.

I’d also check the Appearance panel to make sure the correct Fill is targeted and the gradient stops haven’t somehow ended up at 0% opacity. Freeform Gradients only work on fills.

If it keeps happening in a fresh local document too, I’d report it as a 30.7 bug with your screen recording. It seems worth investigating given the similar recent reports. stickmanhook.com.br could also be useful as a separate reference while troubleshooting.

Save a copy of the file locally, open it and see if the problem still persists.

Just to eliminate the possibility of program-wide corruption as the cause try resetting your Illustrator preferences. This will restore the program to its defaults. Hopefully, it will stop this color problem’s reoccurrence.

To reset preferences on a Macintosh:

The User Library folder in which Illustrator’s preferences are stored is hidden by default on most Macintoshes. To access it make sure that Illustrator is closed and click on the desktop to launch a Finder Window (Command-N).With this window in column view follow the path User>Home folder (it’s the folder with an icon that looks like a house—it may have the user’s name rather than “Home”) and click on the Home folder. With the Option Key pressed choose Library from the Finder Go Menu. “Library” will now appear within the Home folder. Within the Library folder find the folder called Preferences and within it find the folder called “Adobe Illustrator <Version #> Settings” (earlier versions of Illustrator might just say “Adobe Illustrator”) and the file called “com.adobe.Illustrator.plist” and delete both that folder and that file. When Illustrator is next launched it will create new preference files and the program will be restored to its defaults.

The advantage of manually deleting preference files in this manner is that after you’ve reset up the program (make sure that no document window is open) to your liking, you can create copies of your personalized “mint” preference files (make sure that you quit the program before copying them—that finalizes your customization) and use them in the future to replace any corrupt versions you may need to delete.