Hey there, Alix,
Thanks for posting in the Apple Support Communities! It looks like you have a mophie 3-in-1 wireless charging pad by Zagg, and it frequently will only charge your Apple Watch. We're happy to help!
Zagg actually has a support article on their website regarding this exact issue: Why is my 3-in-1 wireless base only charging Apple Watch? – Welcome to ZAGG Care. Check out their solution below:
"If you try to use your 3-in-1 base and notice that only the Apple Watch charging function is working, double check and ensure that the charging cable is fully inserted into the base. If the barrel connector is not fully inserted into the charging base, charging will not function correctly."
Should you still need help after that, please get in touch with Zagg directly. You can do that here: Contact Us.
Have a wonderful day!