Race allows character to cast True Strike as a Bonus Action = Charisma Modifier.

I can get it to work and show on the character sheet, but I don't get the neat little box next to the spell, like Enlarge/Reduce does for Duergar.

How do you get it to display?

For the racial spellcasting where you get a free use and then can use spell slots, they create two entries for it.

That's how I have it setup, but maybe because its a cantrip it doesn't give the boxes?

Are you talking about the box that says USE

that shows up because leveled spells only have limited uses per day. You can't run out of cantrip uses, that is the whole point of them being cantrips.

no, under features, I was hoping there'd be a box that you could check when you cast it that way.

This is how I got it to work. It shows this on the character sheet. Make sure you have a reset type:

Did you do that under Actions or Spells?

If I do it under Spells, I am not getting that result.

I did that under Spells.

Edit: It was on an ability that also had charges. When I tried it on its own it behaved as you described.
Edit2: I added a leveled spell (Enlarge/Reduce) and the boxes showed up, so it must be because it is a cantrip.