can not create appointment in Epiphany

For most web browsing I use Firefox and have always used it to log into phpsi. Today I logged in using Epiphany and although everything displays correctly, including the green colour change as I mouse over the time slots, when clicking on a time slot nothing happened. I tried refreshing and closing the browser without success. Logging in with Firefox allowed me to make the booking. Is there a known issue with Epiphany? Has this come up before for anyone else? Does anyone use Epiphany without problems?

The only mod I have made is to add captcha to the sign up form.

ps. I still think this is an incredible project and thank Nick and the many others for making this project possible and available.