Hey @efmdaniells ,
Thanks for your message! That's indeed an odd one and I'm sorry to hear you are not able to buy any Apex coins from within the game via the Steam Wallet.
Could you let us know if you can log in just fine on your EA account via www.ea.com or www.origin.com and whether other Steam payment methods work just fine and it's only the funds on the wallet that cause issues?
- EA_Neil