Same here for our team, with a number of the sites we manage – that auto-updated to 5.4, now don’t work – with customers clicking the Send button multiple times, sending off a ton of email to clients. The confirmation no longer appears notifying them. We’ve rolled things back but then there was already the other weird issue with the coloured box appearing below the form box at all times. Ugh, I hope these guys get this one figured out. It’s costing us time.