The issue with the water turning red is something that I’ve never seen before. My guess is similar to yours: This is probably caused by some specific issue in your project. It could be somehow related to the Editor View Mode, or that some Developer Show Flags are enabled. But it’s strange that the issue is appearing in game, and not in editor. Did you modify the Water material in any way?
About beach foam: At the moment I’m working on a transparent version of Physical Water Surface with beaches, but the development is not yet finished. In the meantime, please have a look at the following link, it’s a very simple method to make beach foam: https://forums.unrealengine.com/deve…am=&viewfull=1