changing date in invoices always reverts to Dec. 2018?

I received an invoice yesterday so I was going to add it, but when I try to change the date to yesterday, it always reverts to Dec. 19th 2018, it did not do that before, is it a bug maybe or am I doing it wrong?

The field accepts the date if I change it in the calendar, but as soon as I switch focus, it changes to 2018, I tried copy pasting it, but it's not working either. This happens on completely new invoices as well as already existing ones, I'm using Chrome, but it's also happening in Firefox, any ideas?