Unable to toggle on contacts in icloud

I've just bought a brand new Iphone 15 pro. I synced and transferred all the data from my old phone (iphone 6 s plus) and there wasn't any problem except with contacts. I went to the setting of icloud and once I tried to toggle on contacts, it won't green up it just keeps loading for several minutes then goes grey again. I made sure I signed in with the same apple ID and with the same Email. I also updated IOS to the newest version but the problem won't be solved.