Question Detecting a removed image trackable again [5.0.6]

Hello

For short context/scenario:
We have an AR session that occasionally uses image tracking to find anchor positions and place objects. Once properly anchored the image tracking is no longer required so we deactivate it as well as its trackables.
There are certain points in our application were we require to level the field and fully reset the AR session.
Since 5.0.6 this works mostly like a charm.

The problem arises as soon as we re-activate the image tracker manager after a session reset. In this moment the tracking and its trackables get reactivated and the trackables get removed (this seems only to happen on Android, not on iOS).

Once a image trackable is removed it seems to be impossible to get it added again. How can we add it again? We need sometimes to find an image again that was in use before the session reset and can't do so as the imagetracking manager refuses to send OnTrackedImageChanged events for trackables once removed.

Additional Info:
OnTrackedImageChanged fires for each removed trackable once with the trackable beeing in eventArgs.removed - even after multiple ARSession.Resets.

 

EDITED. This post doesn't answer the question.

This is how ARCore works and the workaround is to check the image tracking state.
https://forum.unity.com/threads/tracked-image-wont-go-away.822249/#post-6803699
https://forum.unity.com/threads/arf...ot-being-tracked-anymore.910763/#post-5972075

 

This is not about visibility. I can't check the state as there is no place where i could check it.
After OnTrackedImagesChanges fires with them in eventArgs.removed the event never gets fired again. They are literally removed from the manager trackables after a session.reset.

 

Sorry, I didn't give enough attention to the question.

If it worked before 5.0.6 and now it doesn't, it may be a bug actually. So after the image removal event, the manager doesn't contain any images anymore and doesn't track images, right?

 

Yes. They are not in the accessible manager trackables anymore and don't track at all/don't get recognized anymore.

Interestingly if I track another image then (as expected that one gets recognized/tracked) and do another ARSession.Reset() the OnTrackedImagesChanged removed event fires twice, once for the first trackable and once for the second - so the manager has still to have some knowledge somewhere about them.