When you section edit into WT, the editor's switch button just brings you back to the editor the first time (but then works the second time).
Related Gerrit Patches:
|mediawiki/extensions/VisualEditor : master||Remember switching into VE from WT when discarding changes|
looks like it is happening when when you try to switch from WT to VE and have the single edit tab preference of remember-last and one of the following is true:
- You made no changes and were not on action=submit
- You made changes but opted to discard them (likely if you were section editing)