I think there is a problem with WhatsApp adaptability. Whenever I put my sim in a new phone, it takes a few days to work, I had this problem when I switched from S24U to S25U, WhatsApp refused to work for a few days, than it started to work. I kept registering my phone number and nothing. Also when I came back from holiday abroad it logged me out of all my devices and I lost previous conversations, all that without any notification. Nowadays, sometimes if I receive a message on a device, on other devices that same message would not load. I think WhatsApp and FB are doing updates to their platforms at the moment, because I've got something new going on WhatsApp, and FB is messed up again, especially the messenger platform. My advice is you give it a few days although it might feel frustrating, I don't think it's your phone’s fault. You don't have to do factory reset on your phone, you can do a wipe cache partition from recovery mode and it will only clear unnecessary cache data safely without touching any of your important data from the phone.
