The bug
If one does attempt to import exported world settings from a debug world that was previously generated, a world with default settings is generated instead.
MC-185170
Debug worlds can't be generated using exported world settings from preexisting debug worlds
Resolved
Won't Fix
1
(Unassigned)
Confirmed
Debug, World generation
20w21a, 20w22a, 1.16 Pre-release 1
Retrieved
The debug world is a hardcoded feature which has nothing to do with normal world generation settings. What were you expecting to happen here?