Palace Purple is a micrantha cultivar and those tend to be less tolerant of summer heat and humidity than those with H. villosa, americana or pubescens genes. But that is from the literature only :-) I have no first hand experience as my summers are neither hot nor humid and any heuch does well.

I tried 'Palace Purple' a couple of times and both times it kind of melted away in the August heat. They sell it at the local garden centers but it doesn't do well here for me.

I know I have less humidity than you but I've had luck with 'Carnival Silver Streak', 'Brownies', and 'Caramel' among the non-green ones I've tried. They all have Americana and/or Villosa in their parentage.

Well if they didn't do well in the upstate then I have no chance! Haha. Thanks yall, even though I like them I will wait

Except for the very pale colored ones (like Lime Rickey), they will grow in full sun in my location. And the dark leaved ones maintain their color better if they receive a lot of sun. Generally the recommendation is that heucheras need an organically rich and consistently moist soil so I doubt it is a lack of humidity that is causing issues with any commercial plantings but rather that the soil is allowed to dry out too much to keep them happy.