ObiFluid (7.0 in this case) prints a lot of shader warning to the console upon entering the play mode.
I suppose these can be safely ignored. However it's very inconvenient to develop/debug anything when your console is spammed like this.
Typicial warning is:
Shader warning in 'ParticleGrid(Clone)': signed/unsigned mismatch, unsigned assumed at kernel BuildFluidDispatch at ParticleGrid.compute(359) (on d3d11)
One possible solution seems to be adding this in MathUtils.cginc:
#pragma warning (disable : 3203)
#pragma warning (disable : 3206)
But I don't think it's necessarily a good idea, and even if it is I'd hope to get it officially fixed, otherwise I'll have to manually put these lines every time I upgrade Obi version.