ya I'm experiencing this problem as well, spent 3 hours making a map just for everything from this mod to be deleted... sucks that it doesn't work with the map builder

I'm experiencing a similar problem that when you place a sea luxury resource then come back to the saved map file, the luxury resources are gone along with the resource placement option on the right bar. Bonus resources will load normally.

i assume it has something to do with the fact that it's modded as a game mode and not just a regular resource pack??? I dont know the reason behind the decision to make it that way but basically having this game mode turned on causes a script to run at game start that refreshes the ocean instead of you just being able to import resource placement from the map data. BUUUT if you DON'T turn on oceans game mode.....then even if the resources are in the map data and you have the mod activated ...it won't read them into the game because the game mode is not activated so if you want oceans in the game on a world builder map you have to sacrifice control of the resource placement in the ocean. Exceptionally unfortunate if you took a lot of time making your map.

Recently, this has been making me unable to load my maps when activated. I have new mods, but the ones I enabled work without this game mode being activated for some strange reason.