This demonstrates what I believe to be an error in the memory package of VUnit 4.4.0. Notice that the 8-bit wide tests pass, but as the data bus widths increase the tests fail. They don't seem to fail in the same location either. It is best to look at these in GUI mode after an initial run on the command line. The tests are controlled through compsite generics in and through run.py.
My configuration: VUnit 4.4.0 Python 3.8.5 Modelsim DE 2019.2