Very unexpected /confusing issue with Illustrator today.

I cut and pasted a symbol from one document into a new doc. I tried to apply a new color to the symbol and it wouldn't work.

The appearance panel showed the objects as black, the objects on the pasteboard were brown, and when I selected them, the fill color in the toolbar showed yellow.

I broke the link to the symbol and tried to apply that yellow color to the compound path—it wouldn't work.

I released the compound path and tried to apply yellow to the individual objects—it still wouldn't work.

Rebooted Illustrator. Didn't help.
Rebooted computer. Didn't help.

Restarted Illustrator, went into the original symbol, and went into the symbol, cut and pasted the paths into the new doc—still wouldn't work.

THEN... I noticed I was pasting the paths onto an empty layer named new symbol 2, so I pasted the paths onto a new layer and the colors were correct!

SO DEVS, I don't think this is a logical workflow. There is no indication on the appearance panel that a color was applied to a layer, so it's near impossible to tell what's going on.