Using 5.3 with Lumens and was happily editing the landscape when I started to get these strange artefacts on the landscape (top image). If I go into landscape mode and make a slight adjustment, such as smoothing and then come out of landscaping then they go away and looks like it should (bottom image). If I save and close however they come back when I reopen. Any ideas pleas as it is beyond my knowledge.
Well, it would appear turning off nanites in the project settings cures this but of course isn’t a real answer as it leaves me with no Nanites and error messages regarding Nanites being not enabled. So, as an experiment I went to one of my large meshes and made sure Nanites was disabled for it, then switched Nanites back on in Project settings and rebooted. Went back to my large mesh which was happily sitting there and enabled nanites back on for it and the thing just vanished, one big hole where it should be! I guess some sort of shader rebuild is required but not sure how to do it. frustrating!