Does it have a proper progress bar when generating textures? I've quickly tried on my pc and it seems to work correctly.
Also, to be clear, when you say 'completely smooth', that mean no height maps? everything at the same level?
Can you also make a try with Random seeds, colors and all sections (no basics, no advanced) to see if it's link to some extremely bad values.
On a personnal note, I really dislike that batch generation I think that it's a bad way of working, you'll probably have 10% of nice planets doing so, and it's quite optimistic
Anyway, can you send me your log file after the export, it should be in SteamLibrary\steamapps\common\Grand Designer\GrandDesigner64_Data\output_log.txt. Send it to bug(at)ignishot.com, I'll check what's going on ...