Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2070 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.92
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-01 20:37, hash: rB1d4bae856690
Worked: (newest version of Blender that worked as expected)
Short description of error
The little cell size indicator in the mantaflow domain object does not accurately reflect the actual cell size when the domain shape is changed. If you change the shape in the edit mode, it doesn't update size or shape. If you scale and then apply the scale, then the longer the side, the smaller the diminsion of the box. So a very long domain axis will have a very narrow box along that axis.
Exact steps for others to reproduce the error
create a mantaflow domain, change its size.