Eyedropper Tool picking wrong colors in Keynote 8.1

Hi All,

I'm currently using Keynote 8.1 in a MacBook Pro with High Sierra. Recently, I noticed that the eyedropper tool wasn't being able to pick the right color. I took a print screen from a color I needed, pasted at the slide and tried to use this color as background. It gave me a different tone of yellow, establishing clear contrast among the image I pasted and the color it recognized.

I even used the system's Digital Color Meter to confirm: colors are different.

Does anybody had this trouble and know how to solve it?

Thanks a lot,

Gabriel