Hello, i was also facing this problem and I was not sure about which particular setting I changed or this might be occur due to installation of wrong version of Sublime ( i think ).

And you will see that autocomplete suggestions will appear only when you press CTRL+Space.

Solution

Here is what i did :

Step 1 : Open Sublime text editor.

Step 2 : Go to Preferences ( top left side of Sublime).

Step 3 : Go to settings.

Step 4 : Copy and paste the following code in settings box ( right side of settings)

"auto_complete_selector": "text, comment, string, meta.tag - punctuation.definition.tag.begin, source - comment - string.quoted.double.block - string.quoted.single.block - string.unquoted.heredoc"

Hope this will help you <3