Can't access Yahoo on other devices

I have a problem with my Yahoo account. When I try to access it on any device other than my desktop, it prompts me for mobile verification code (four digits). A code is sent to my mobile number, but when I try to key that code in, Yahoo doesn't recognise it! It obviously has the correct phone number or it wouldn't be able to send the code to my phone in the first place. I can't even sign into Yahoo on the mobile itself!
Is there a way round this? I don't want to do anything which could stop me getting into the account on my desktop.
Unfortunately, my Yahoo account is linked to my PayPal account, otherwise I'd be tempted to give up on it altogether.
I'd be really grateful for your help.