Enter moves the cursor without scrolling the screen until the cursor is close to the bottom of the window.
Then data scrolls up such that the cursor never gets to the bottom.
Can this bottom scrolling be automatically stopped via a set command?
You can control the number lines using the scrolloff option:
set scrolloff=0 More information with `:help 'scrolloff'
vimrcshould also prevent this. If avimrcis present,defaults.vim(which contains:set scrolloff=5) will not be sourced.