I can't see painted landscape material until I save the level

Today I have a real strange problem that I can’t seem to fix. I created a landscape material and a sculpted a new landscape. I create the layer info for each material and want to start painting. But I don’t see any material being painted. Only when I click SAVE CURRENT suddenly all painted landscape shows up. Also, after I build lighting, the material layers under paint (where I usually see the materials) grey out. I really don’t understand this and it is driving me nuts. I can click on one of the materials and continue painting. But I don’t see any painting happen. But as soon as I click again on SAVE CURRENT, all the painted stuff suddenly shows up. What the heck I am doing wrong. I had no problems with landscape materials painting over the last view days and now it suddenly it almost as if the engine broke.

Thanks for you help.

Could be lots of things.
the first thing you should do is save everything and reboot the PC.
if it still happens you can export the landscape heightmap and simply make a new one with it.

If the problem persists after that, then describe the additional steps you took.