there is a possibility cause this to happen,the underground villages conflicted with the lake/river/ocean.when world trying to generated the lake/ocean/river and the underground village it conflicted

it's just annoying travelling the flowing water

Mod version:1.1.0

Fabric API version:0.29.3

Minecraft version:1.16.5+0.11.3 Fabric Loader

Next update (V1.3) will finally solve this issue.

I am also having this problem, running BYG, Lakeside and River Redux.

I am uncertain how exactly to fix this but I have some ideas for the future.