In the MitkNodePredicateGeometry to precision is set to 1e-6. So this is at least one of the issues why the old masks are not found. It could be an option to relax the precision, but since the rotation matrix might have a large effect even for small inaccuracies, it needs to be thoroughly tested first how big the effect is if. e.g 1e-4 is accepted.
For now, the new segmentation masks are provided as test data instead of the old masks.

I compared the geometry of the dynamic image, the old mask (which could not be found anymore) and a new mask (is found), using the Details info box in MITK. I found small differences in the geometries between the old mask and the dynamic image, but not between the new mask and the dynamic image. Namely:
Spacing:
dynamic image: [1.0156, 1.0156, 5.99998]
old mask: [1.0156, 1.0156, 5.99997]
new mask: [1.0156, 1.0156, 5.99998]

Undo/redo is a known problem, covered by other tickets.
The crash propblem I was not able to reproduce.

How to adapt: Use the "clear label" option in the context menue of the label inspector.

Deleted branch from rMITK MITK: bugfix/T30414-MakeIndexDefaultPage.

Pushed new branch to rMITK MITK: bugfix/T30414-MakeIndexDefaultPage.

In the past we used the XLST functionalities from Qt 5 to remove certain parts for the help files. Since Qt 6 we removed the transformation as it is not easy to set up a feasible alternative with libxml for example. The downside now is to have a little bit more clutter in the Help Contents. Since the Help Index still looks like the Help Contents before, I think we should simply change the default view of the Help Perspective to Help Index and live with the Help Contents as-is.

Deleted branch from rMITK MITK: bugfix/T30416-AddUsageHintsToMeasurementView.

Deleted branch from rMITK MITK: bugfix/T30413-FixBlankHelpPages.

Pushed new branch to rMITK MITK: bugfix/T30413-FixBlankHelpPages.

It is not straighforward which name to use, since what is displayed in the Image Navigator depends on if the dynamic image has been globally or locally initiated. Therefore, for now we keep the name "Time" in the Image Navigator. What is shown is therefore not obvious for the user and should be documented clearly in the F1 help. It needs to be checked if this is the case.
A solution could be to provide a separate slider in the ModelFit Inspector View.

RFD result: Remove the functionality

This is a good idea.

hm. I see.
May be:
B + if you press shift while hovering, then always highlight?

In T30417#258666, @floca wrote:

That you cannot tell. You don't know how testers would react to option A. May be it is equaly irritating to them. And may be they would missing the highlighting of invisible labels if the realy would work with it... 🤔

In T30417#258648, @kislinsk wrote:

but the disadvantages proved to outweigh.

That you cannot tell. You don't know how testers would react to option A. May be it is equaly irritating to them. And may be they would missing the highlighting of invisible labels if the realy would work with it... 🤔
If we want to base it on user feedback in such an unclear situation, one would need to offer/explain all options and let them choose/poll.

Pushed new branch to rMITK MITK: feature/T30426-doc-updates.

Hm, yes, As we also define a reference image like in the segmentation view. I think it is the most pragmatic and consistent approach to introduce the same/simelar behavior:
warn users if the rendering is not alligned with the reference image and only allow making planar figures if the geometry was reinit.
I am not sure if reinit as soon as the click on a planar figure button wouldn't be irritating.