Bug using Camunda Date

I am working with Camunda 7.7.0 and tried the same with 7.8.0. When a variable of type Date is set the value returned is always null.

I set the value:

In the next step is always null.

I tried to pass the value as a String in the format yyyy-MM-dd’T’HH:mm:ss and using new Date in javascript:

camForm.on(‘submit’, function() {
variableManager.variableValue(‘instructionDeadline’, new Date (insDateVal));
});

Also tried new Date (insDateVal).toISOString() but it returns a format error.

Thanks in advance.

The date is there but it is not shown since is a Date and Camunda do not convert it to a String