I've got a homebrew puzzle of my own.

Trying to recreate a Dragonborn feat from UA: Dragon Wings, it didn't make it into Xanthar's.  So I took Dragon Hide, left the prerequisite the same, adjusted the flavor text/description and the mods. Looked as you'd expect. Except my Dragonborn Test PC couldn't see it (not in feat list). I go out and remove the pre-req and I can see it and it applies fine (move spead shows).  For this instance since its an in house use which is fine, but frustrating. Anyone have any thoughts?

I can confirm that with either a feat copied from Dragon Hide, or a homebrew feat from scratch, the prerequisite of "Race - Dragonborn" prevents it from being usable by a Dragonborn character.

I've tried and have outside confirmation from someone other. If we attempt to make a homebrew feat with the racial pre-requisite dragonborn, dragonborn can't actually use it. Its been tried from ground up (new feat) and based off an existing feat (Dragon Hide). Same results in both cases. Dragon Hide as is works fine, but the instant you use it as a template to customize it stops working.

You've checked to make sure the character has homebrew enabled, right?  Yes, of course you have, because you said in one of the other threads that you tried with and without the prerequisite and it worked without the prerequisite.