Changed grid value is not saved
Description
Reported by Siebe Bosch (Hydroconsult.nl).
I open an asc file as a grid and change a grid value when I save the grid and reopen the value is not changed. But only when I open the grid with InRam=false. When InRam=true the changes are saved.
I created a unit test that is confirming this issue.
Environment
None
