Can't Save New Contacts To Phone

Recently I've noticed my phone will not save new contacts I add to my phone. If someone calls/texts me and I try to "Create a New Contact" I am able to originallyl but after a day or two it is erased and just shows the number again. I am up to date on all software (13.5.1).

This has gone on for a few months now and I'm not sure how to fix it. It is quite annoying to not be able to add any next contacts to my phone.

Thanks.