If you have a layer group that contains only one item, attempting to use the Move to Back/Front slider crashes the app immediately.
Steps:
1. Have a Layer group that includes one item. (I ended up this way by having two layers in a group, and I deleted one of the layers at some point.)
2. Select the nested layer.
3. Choose the Arrange tool.
4. Click the Move to Back/Front slider in the Arrange panel.
Crash.
When there is more than one layer in the group, the tool behaves as expected.
Perhaps one way to treat this situation is that if a layer group is down to just one layer, it no longer behaves as a group?