So I was gonna make a new sort of player race for my campaign in the Homebrew creator and use the Variant Aasimar included in the basic rules set as a base. Problem is, when I went to use it, it wasn’t listed alongside the other bases for Homebrew races, sub races, or variant races. Am I missing something or is there a reason for it?

Are you selecting it from the correct drop-down?

Create Race >> Create Variant

There will be two drop-down boxes. The top is for base races to create a new variant from scratch for that base race. The bottom one is for selecting an existing variant. You will be wanting to use the bottom one.

Just checked, works perfectly for me.

Ok, thanks, I must have had a little bit of a brain fart moment before I posted this. I kept hitting the box that chooses which race to make a variant for, didn't quite click. Must have been an off day.