I did my best to tweak the Arcane Trickster subclass so that the only change is that it uses Cha instead of Int.

I had just finished editing a variant race option and after much head scratching, got it to work.

My boi for reference https://www.dndbeyond.com/characters/114424041 (I hope that work I get a Rylzrayrth message on incognito) 

After hours of work on both homebrews I'm hit with the beholder error anytime I try to add a spell.

Error Code: b0925ccb94484f719e4e6ee2d73f24a7

Reading other form posts I'm sure this is a subclass error somewhere but since I can't make a true copy of arcane trickster to go by I'm at a loss for what is wrong.

Any help would be appreciated.

Did you attach any spells to the subclass? If so, how?

I did not attach spells to the class itself. Just set the class to "can cast spells".

There’s your problem. Please see the Homebrew Subclasses & Species FAQ #7 for a link to a walkthrough that will help: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).

Well now it seems to work? ... All the spells I had equipped with the vanilla ArcaneTrickster just popped into my spell list and it seems I can delete and add freely now? Guess it just needed an couple hours to adjust?