[DevExpress Support Team: CLONED FROM T110105: Master rows are collapsed when the ListChanged event is raised]
Actually, it is broken in 17.1.7. If you edit and post on the master record while the detail is expanded, the detail, while the detail itself remains expanding, all the detail records disappear from the display.
With 17.2.7 this doesn't occur and works fine.
[Updated]
It doesn't always work in v17.1.7 through 17.2.7.
In your demo it does. In most of my apps it does. But if the master row has one and only one field, and you edit and post the changes to that field while the detail is expanded, while the detail itself remains expanded (show columns heads for the detail), all the detail records/row collapse (there are zero records displayed).
Picture attached.