Lately whenever I summon a popup in the Appearance palette, I will often find that Illustrator locks up with a spinning rainbow pinwheel. I have waited a while for it to return and it never does; I now consider this a cue to restart Illustrator and hope I saved recently, or that I got lucky with the crash recovery.

The two popups I get it with more often are the stroke/fill color, and the stroke. I've included screenshots of both to make it more obvious where to fool around. Next time this happens I'll come provide a file that does this.

I've heard some reports of this happening with popups invoked from the Properties palette, too. I never use that myself.

I'm currently using 2022 Macbook Air running Sonoma 14.1.2, and Illustrator 27.8.1