This happens because Emmet tries to respect default ST completions and due to lack of API support to properly handle built-in snippets: https://github.com/sergeche/emmet-sublime#tab-key-handler
By default, Emmet will not expand abbreviations by Tab if there’s autocomplete popup visible to allow users to work with default ST completions and snippets. You can override this behavior:
- Go to
Preferences > Settings — User
- Add
"disable_tab_abbreviations_on_auto_complete": false
option. Make sure this file contains valid JSON.
After that everything should work fine, but you’ll no longer able to complete items from autocomplete popup with Tab key, use Enter key instead.