When a list from Tasks.org is synced with Vikunja, the relationship between the parent and child is not preserved. I have to manually click on each subtask and then select the relationship to the parent tasks. And then the tasks are still displayed at the same nesting level as the parent tasks, which at least to me is less visually clear.
What is the expected behaviour for Vikunja when importing nested task lists from Tasks.org? Is the parent/child relationship not being preserved a bug?
This sounds like a bug.
I have the same issue but in both ways. I’ve setup vikunja over caldav in the tasks .org App
Vikunja → App
Create a main Tasks with 2 subtasks in Vikunja. On the mobile i’ve got 3 main tasks which are not related to each other
tasks.org → Vikunja
Create a main Tasks with 2 subtasks in the tasks.org app on the mobile. Vikunja Webinterface shows 3 main tasks which are not related to each other
Vikunja:
I had a look at the ics file directly. A Task with a related subtask looks in the ics file:
BEGIN:VTODO
UID:a89d3f96-5ca2-4f1a-9254-d63371d5cb08
DTSTAMP:20220823T074318
SUMMARY:Main Task
CREATED:20220823T074318
LAST-MODIFIED:20220823T074318
END:VTODO
BEGIN:VTODO
UID:2d57879b-57f7-4b05-a9ce-245b9fa910d4
DTSTAMP:20220823T074339
SUMMARY:Sub task 1
CREATED:20220823T074332
LAST-MODIFIED:20220823T074339
END:VTODO
There is no relation between this 2 tasks on the caldav interface. I think the “related-to” property is missing: Caldav - related-to
The same happens when creating a task with a subtask on the mobile and sync over caldav. I get 2 PUT entries in the log of vikunja. When looking at the 2 ics file from the puts, there are also no relation properties.
Task:
BEGIN:VCALENDAR
VERSION:2.0
METHOD:PUBLISH
X-PUBLISHED-TTL:PT4H
X-WR-CALNAME:
PRODID:-//Vikunja Todo App//EN
BEGIN:VTODO
UID:4027433967034655023
DTSTAMP:20220823T075316
SUMMARY:Main mobile
CREATED:20220823T075316
PRIORITY:9
LAST-MODIFIED:20220823T075316
END:VTODO
END:VCALENDAR
Subtask:
BEGIN:VCALENDAR
VERSION:2.0
METHOD:PUBLISH
X-PUBLISHED-TTL:PT4H
X-WR-CALNAME:
PRODID:-//Vikunja Todo App//EN
BEGIN:VTODO
UID:1426114611077990589
DTSTAMP:20220823T075316
SUMMARY:Sub mobile
CREATED:20220823T075316
PRIORITY:9
LAST-MODIFIED:20220823T075316
END:VTODO
END:VCALENDAR
Looks like it, yes. Thanks for digging this up.
Hello, has this been solved / is it working properly in the current version?
Thanks!
Not sure, I didn’t test it recently. Does it work for you?
Can confirm that this is still an issue with : v0.21.0. Creating tasks with subtasks on either side still shows them as unrelated to each other. 
I’ve pushed a potential fix in bfcefa0217 - please check with the next unstable build (might take a while, we currently have issues with our build process)
This PR has recently been merged with a few improvments for subtasks: #1634 - feat(caldav): Add support for subtasks (i.e. `RELATED-TO` property) in CalDAV - api - Gitea