I have a similar problem but in my case auto activate in buoyancy component did not work . I tried to modify buoyancy coeff. increasing it to without any effect. btw the object mass i set to 8 (kg?). Pontons radi set to 10 (but using 100 also does not work).
The only major difference between my code and many example I see is that I’m using a pawn and not an actor … but this should not be a problem.
I tried also to use WaterTestMap in Water Plugin content folder using BP_BuoyancyExample but it just sinks.
I tried on 4.26.2 using Water plugin contents and it seems to works but if I create a simple cube with buoyancy (in the same level) it sinks all the times… the only way to make it work is to use EditorCube as static mesh.
I cannot understand where’s the fault but it sounds like a big-beautiful-bug…