It is not related to the latest changes in the release branch. Same applies for last snapshot installer and v2018.04.

- Set a dynamic reference image like U4DCyl.nrrd
- Static segmentation
- t = 0
- Preview works, resulting surface works but has default geometry with 1 time step starting at 0 with 1ms duration

- t > 0
- Preview only shown in t = 0, same for result

- t = 0
- Dynamic segmentation
- t = 0
- Preview works, resulting surface works but has default geometry with 1 time step starting at 0 with 1ms duration

- t > 0
- Preview works, resulting surface has as many time steps as the one where the interpolation was done. For example: interpolation done in t=1, but image has 4 timesteps. Surface has 2 time steps.

- t = 0

- Static segmentation

The resulting surface is always overridden. Even if it is renamed in between interpolations! Interpolation surfaces in other time steps are not preserved, i.e. one can only have a surface in a single time step.

This also reveals another bug in the 2-d surface mapper. While the 3-d surface mapper correctly shows a surface in a certain time step, the 2-d mapper shows the surface for all time steps. But only after it has been viewed in the correct time step.

I also got twice an unknown exception while playing around with interpolation, segmentation, and time steps with 3D+Heart, but I cannot reproduce it.