I have found some ore patches which abrupltly end at the water edge. This seems to happen only for Vitamelange and Cryonite. All other ores added by Space Exploration and Krastorio2 are working fine. I can Provide a save file if necessary.
I'm using the latest version off all three mods and using the latest Steamversion of Factorio. Operating System is Windows 10. If more information are necessary just ask.

The mod allows spawning in water tiles by removing the collision mask, but it does not remove tile restrictions on resources for where they are allowed to spawn. Cryonite can only spawn on ice tiles, and vitamelange has a list of grassy tiles where it can spawn. You would have seen a similar issue with vulcanite in SE 0.5 only spawning on volcanic tiles, not sure if it still spawns the same in 0.6 though.

That is good to know. Yeah now that you mention it, the tooltip even says that. That would also explain some other abruptly ending ore patches. And in SE 0.6 Vulcanite still has the same restrictions. At least according to the tooltip. I'm not sure that the biome on the vitamelange planet could be described as vulcanic, maybe smoldering.
Thanks