Working in Mojave 10.14.6 on a iMac 2017, 3.5Hz

I needed to alter a swatch I had made using vector artwork I have drawn, the swatch was created in Illustrator 2017, and though complex, had no issues being added to the swatch palette, or used. I had edited it a few times to get the elements into the right place and adding it back to the Swatch palette.
I tried editing in Illustrator 2020, which we have been running across our Macs fo the last few days, and it will not add back in. I can drag it out, but even though it looks to be adding back in when I drag it back, it doesn't appear. I tried a simple swatch, no issue. I restarted and it still won't add in. I had to go back to Illustrator 2017 to make the change and add the swatch back in.