I’ve gone through and made a homebrew subclass based on the Eldritch Knight twice at this point and for some reason the ability to cast spells just stops working when I get it finished (this is also when it stops telling me that the subclass is too similar to the original). What is with this glitch?

The spell slots are available and I changed the subclass name (this time, I didn’t notice when it happened the first time) and when I go to the character builder the spells tab just vanishes. 

The one I published is Tiny Wyrm Sidekick. As far a I noticed (I wasn’t running a character in the builder to track it.) it went away when I settled on the name as well.

I didn’t have a spellcasting trait named spellcasting.

 This link is to the now working version. Thank you  Cyb3rM1nd!

https://www.dndbeyond.com/subclasses/2401705-tiny-wyrm-sidekick

You need a feature named Spellcasting

Without it you won't get spell slots.

This fixed it. Thank you so much!