Hi kroberts4,
welcome to the Apple (user-to-user) Community.
Re: "notification in settings: "Some account services will not be available until you sign in again"
even though I am signed in. ... ... "some account services remain unavailable. Any ideas?"
Mmm... not easy to just guess ...
Wondering where you are signed in, and if you are signed in (to your iPhone) with your Apple ID:
Sign in with your Apple ID - Apple Support
✽ Try re-starting your iPhone (Deletes temporary files, and can often restore order)
✽ If you want, you could try signing in to your Apple ID account online, and check all is up-to-date.
Apple ID Log-in : https://appleid.apple.com
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Else: if you have changed your Apple ID or Apple ID password recently:
✽ You may need to sign out of Messages, and FaceTime, etc, and sign back in with the updated Apple ID.
Or ... if the App Store is unavailable: If you can’t download or update apps on your iPhone or iPad - Apple Support
All the best :-)