I had the same issue with Zore -I'm no expert, but it looks like that's got something to do with the fade distances that are specified in the config file. I messed around with them for a bit with no luck. What ended up working for me is changing the template body from Gilly to Minmus in zore.cfg. As far as I can tell it fixes the fade in issue without changing any of the properties of the planet.
TL;DR just open the config file for zore (and presumably any other offending planets) and change This:
Template
{
name = Gilly
removeAllPQSMods = true
}
To This:
Template
{
name = Minmus
removeAllPQSMods = true
}
Check that it doesn't mess with the terrain. It didn't in my case, but that might not be true for every planet.