Updating task failed (dates)

[maxlStone]

What Happened?

Trying to save a task with start and due date gives an error.
The task has a start and a due date that I configured in Nextcloud tasks app.
The due date is after the start date, otherwise it's not possible to create the tasks.

Test task has a start date of 11th october 2021 17:00 (5pm) and a due date of 15th november 2021 13:59 (1:59pm).
I printed some debug output in the TaskModel.update_task method to get the date information. I use the methods task.get_dtstart ().get_value ().as_ical_string () and task.get_icalcomponent().get_due ().as_ical_string (). Both give me the value of 20211115T135901, which corresponds to the due date.

Steps to Reproduce

1. Create task with start and due date in Nextcloud Tasks app
2. Sync with Tasks
3. Open the task and click save without changing anything
4. A error window opens

Expected Behavior

Working normaly

(Happens with compiled version from git and with the version from appcenter)

OS Version

6.x (Odin)

Software Version

Compiled from git

Log Output

HTTP-errorcode 415 (Unsupported Media Type): Sabre\DAV\Exception\UnsupportedMediaType
  Validation error in iCalendar: DUE must occur after DTSTART[exception][message]

Hardware Info

Latitude-E7270
Intel® Core™ i7-6600U CPU @ 2.60GHz
Intel® HD Graphics 520 (Skylake GT2)

[maxlStone]

In TaskRow.save_task(ECal.Component task) the due date due_icaltime is also used for ical_task.set_dtstart(ICal.Time) besides ical_task.set_due(ICal.Time). This does not look correct to me. Leaving the dtstart untouched looks like a solution to me, as Tasks does not provide the option to enter a start date anyways. Correct me if I am wrong.