In a form, we have a Date field. General field type date and Presentation type Date.
Date/time Options Calendar with display patern value text set to system default.
When we use the form, something strange happens: when we set a date, the format works fine, and a date is selected.
But on every other change on the form, the date is set to one day earlier. Despite having no code whatsoever to manipulate that date.
We recently upgraded from 5.4 to 5.9 and since 5.6 we seem to have this issue.
In 5.4 we used this as a field type Date, Presentation type Text (so that is different)
and the same on all other options (Calendar, using system default)
If we configure our field like that on our 5.9 environment, we seem to lose the date mask __-__-____ that we were used to.
and are stuck with an unformatted date, causing errormessages for the users, obviously.
Date field in 5.4

Date field in 5.9
