Can't initiate Tavern missions

[Kreegan]

With Firefox 35.0.1 I can't start Tavern missions - clicking on "Accept" starts "loading" but never goes to the fight itself. Refreshing the page shows that no mission has been initiated. Same with IE10. Clearing the browser cache doesn't help.

Edit: If I click on some other link - for instance the Blacksmith - and then return to the Tavern and accept a mission, it triggers OK but just once (trying to accept a second mission after that behaves like described initially). Clicking on links outside of the Tavern and returning to do missions one by one does the trick as a workaround.

Edit 2: after the daily reset a while ago it seems to be back to normal.