I'm having this issue also and it doesn't spawn desert or deciduous biomes. If I so much as open the WORLD tab to customize the world spawn settings, this bug occurs (even if I don't change anything in the settings). However, if I don't open the WORLD tab, the bug doesn't happen. So, in effect, I can't customize the world at all-- if I attempt to, it just spawns a vanilla world with no RoG content.
Devs, please look into this. This must be a recent bug.
Also, I tried uninstalling multiple times, deleting all .ini files, disabling all mods, etc. Nothing has fixed it.