Which time zone use on your phone, is there any difference in other devices which had regular access to Coinbase? it was a problem for me at one point until I put it on automatic time zone determination.
Thats true, I experienced this at one point and I wondered what I did wrong because. It brought an error message until I did a synchronisation of the account with my time zone and it worked smoothly. So, sometimes its about the timing that makes the code wrong and as such, its best you allow your device to automatically set the time zone and then, you synchronise the app or site with the time zone and your good to go.
Mind you, the 2FA is one way to add extra protection to your account or wallet on a non custodial site or exchange and a good one at that, loosing it would as well bring you trouble so, its best you be careful and see a way of getting back on track with the system.