Pinterest usually displays fine, but sometimes the pins display in only two columns that don't cover the screen. I can live with that, but pins won't save. I click Save, the button registers the click as if it's worked, but it doesn't save and the acknowledgement pop-up window doesn't appear. Also when I read notifications it doesn't register that I've looked at them and just keeps counting up until I view the site on my phone.

I'm running Firefox 50.1.0 on a Windows 10 laptop. I've only just bought it and this problem has existed from day 1. I'm running uBlock adblocker, but I've already turned this off for Pinterest. Other sites are working fine - Pinterest is the only one I use that seems to have a problem. Does anyone have a clue what's upsetting it?