After upgrading to Atom 1.19.0 the package autocomplete-plus does not work as expected (while typing) and the only way to trigger it is manually by the command palette or key-bind.
I double checked all the related packages and settings and everything looks fine.
To be sure is not related with an specific language I tried to get autocomplete-snippet to work, it does not either.
I also tried restarting several times.
This is IMHO a critical bug, basically “intellisense” functionality is broken for every kind of buffer.