The loading screen is what comes up right after I do a fresh install of WhatsApp from the google play store. It never gets further, even with the "exploit protection compatibility mode" turned on.
But now, because you mentioned Airplane mode, I actually turned on Airplane mode, and then tried to use it.
AND...it worked! I don't know what happened, but it got a few screens in (which wasn't happening before), then I got stuck because I wasn't receiving their SMS. Then I turned OFF airplane mode, shut it down and restarted it, and now it appears to work.
Though I don't have any of my messages that I had previously, and I'm not in the groups I had previously.