i'm unsure of your problem but i will tell you my experiences:
When i open the watermill map at map maker and i save it, the next time i open the login, all object dissappear.
Solution: reinstall.
my oldest computer does not show terrain blending, all maps everywhere is sand. even with updated graphics card drivers and switching rendering driver doesn't work.
Solution: Change the computer or the video card with a newer one.
if you can please open the file FH.log at put here all text it has, maybe it can be helpful.