Fluid baking - only a top "blanket" of the surface is mesh-baked

See image below:

The domain is a box that is sat on the grid and that small cube is the inflow. So in old fluid sim it would fill up the blocks like normal water. Does anyone know how to fix this?

Note theres a second image showing the particles if you click the image, and that just also does the top surface too.

Just posted the same issue!

Just tried 2.91alpha and it seems to be working now