Problem with the "Done" Button/Action when using with online task

[lutinjisnotte]

Describe the bug
Error with "done" action when using a CalDAV online agenda

i get an "Unknown error" "HTTP 0" with this description
"PUT https://dav.mailbox.org/caldav/MzM//c53a7369-f547-4225-935d-222cb5a7fea1.ics failed: HTTP 201 Created"

To Reproduce
I connected my CalDav calendar (from dav.mailbox.org)
I created a task on the agenda using Planify.
I checked on thunderbird if it shows there and i shows in thunderbird too.
When i click "done" on Planify for this tasks, i get an error.

Expected behavior
No errors should arise, and the task should update on the Planify app and be synchronized online.

Screenshot

Desktop (please complete the following information):

• OS or DE: Debian / Gnome
• 12 Bookworm

Additional context
installed trough flatpack
Planify version 4.15.2

[lutinjisnotte]

i just found that on the screenshot, the S in the start of the string is not present by default, its only here because i misclicked on the S key. when i repeat, i still get the problem but without the S, so it should be excluded.