PayPal suddenly not acknowledging my account in browser logins

[liz-l]

Today PayPal is suddenly saying it doesn't have an account with my email address when I try to pay for things in web browsers, though I can successfully log in to the app and it let me log in via my account when I went to create a community account in a browser. I am on a Mac and iPhone and have tried four browsers total, on both my laptop and phone. Yes, my email address and password are correctly typed; yes, I have cleared my cache/cookies; yes, the OSes & browsers are up to date. Any other ideas? Thanks!

[liz-l]

Update: I have now successfully paid for something else in a browser, so I'm now speculating that perhaps the issue is on the vendor's end and it's an issue that for some reason the PayPal pop-up box isn't able to properly tell me about so instead it refuses to let me log in to pay. (Not sure if that makes sense.)