We have just reached level 10 in our campaign and i am playing a bard. We have most of the expansions in our campaign including  Xanathar's Guide to Everything so i wanted to grab Find Greater Steed. In the drop down for lvl 10 i can see all some of the spells from it including similar levels spells at level 4 and some level 5 like control winds all from Xanathar's Guide to Everything. But some others are missing like Find Greater Steed and Dawn. Is there a reason or maybe a rule im overlooking?

I was able to select Find Greater Steed with Magical Secrets (10th level). Refresh the page and check again.

You can see erupting earth which is from Xanthars but find greater steed is not there.

Might be easier to see. 

Ok, you need to check if in your campaign the content sharing is activated and you really have access to Xanathar's.

Those spells you mentioned (Erupting Earth...) are also coming from the Elemental Evil Player's Companion which is free.

Check if you can access this link: Find Greater Steed. If you are not able to open it, it means you do not have access to it.

 I was able to get to the link and was able to see all the spells in the DnDBeyond Spells section for Xanthar's. If the spells are coming from EEPC then i guess im missing all of Xanthar from the selection but not from my account. 

As for the campaign yes he does have content sharing on. 

Post here the link address of your character sheet, I'll give a look.

Are you making the character inside of the campaign? You must be using a character inside the campaign to benefit from the campaign sharing.

https://www.dndbeyond.com/profile/AIphaSquirreI/characters/2289497

And yes this character has been added to the current campaign. 

It seems like a cache issue, but I can't be sure.

Anyway, I added the spell in Magical Secret, let me know if you have any more problems.

Thank you!