Turtlewalker, I believe it actually is Dyckia 'Yellow Glow', often mistakenly mislabeled as 'Moon Glow'.

This is a challenging Dyckia to grow, that's for sure. Most of what you need to do is experimentation but here are a few things that might help.

Dyckias need lots of room since they are terrestrials. You need to keep up with the potting. 'Yellow Glow' especially does not like to be stressed which means being in the right size pot and not allowed to dry out and stay dry. Easing the stress may only mean more frequent watering.

I think everyone agrees, full sun on this Dyckia.

Fertilizing seems to be a hit or miss proposition. Fertilize once and then let the Dyckia grow. Sometimes as the fertilizer wears away, it seems to trigger that yellow flush.

I would split some of those 'Yellow Glows' up and pot them generously and see if they fare better than the clumps you are growing. The clumps (if you want to grow them in the clusters -very dramatic when they glow) I would step up to a larger pot.

In Florida we do have a few more months of warm weather but growing season will slow down in another month or so - so I would be judicious about any heavy fertilizer right now. I think I would go with something like Nutricote.

You have enough 'Yellow Glow' to experiment - and, aside from not having the color you want, they all look healthy with wonderful form.

Let us know what happens, please!