Gradient Tool - Unable to Select Color from Swatches

Hi there,

I've been having this issue for awhile and didn't find anything on the forum so I'm curious if anyone else has run into it.

When using a gradient stroke or fill, sometimes Illustrator will not allow me to select a color from the swatches to replace the existing color in the gradient. See screenshot below where I added a stop in the middle, tried to replace it with Magenta, and the color did not change.

I am able to change the color using the RGB sliders, but of course I don't want to memorize RGB values when I have swatches saved right there...

Any help would be appreciated! This is not file specific either, happens on any file. Running AI 28.5, Windows 10.