I cannot register a passkey on my mobile app using SPA

I’m attempting to set up a passkey during account creation with Universal Login.
Upon finishing the passkey setup and proceeding to the Universal Login passkey creation screen, I’m encountering an “invalid-passkey” error, preventing me from creating a passkey.

I’ve verified compatibility on Does my browser support WebAuthn?, where the platform authenticator is indicated as green.

I’m wondering if passkeys might not be supported on smartphones.
Could you please assist me in resolving this issue?

Can passkeys not be used in mobile app SPA?
Or is it not possible to use it due to the device settings?

lead me to a solution

@rueben.tiow @auth_support