Advanced Date Configuration flatpickr not working since upgrade to 6.2.13?

Hi,

Since doing an update to 6.2.13 for Fluen Forms, the advanced date configuration settings I've had working and enabled for months using flatpickr no longer works.  I use flatpickr to enable specific dates on a calendar and disable all others, and this is not functioning any more.

I can't imagine anything in flatpickr code changed, but my current advanced config is this, where all wednesday's are enabled plus specific Thursdays.  The calendar instead is just enabling every single day and ignoring this config completely and I can't for the life of me figure out why.

Any help would be greatly appreciated

{
enable: [
// Specific extra dates
"08/27/2026", // Special Thursday

// Wednesdays except specific date
function(date) {
const isWednesday = date.getDay() === 3;

const isBlocked =
date.getFullYear() === 2026 &&
date.getMonth() === 4 && // May is 4, because months are 0-based
date.getDate() === 6;

return isWednesday && !isBlocked;
}
],

dateFormat: "m/d/Y",
showMonths: 1,
minDate: "today",
maxDate: new Date().fp_incr(60)
}