Can you please be specific on which autocompletion is not working, type, variable, function names, or something else? Along with this a simple code sample would be more helpful for us to troubleshoot.
all of them.
example: i create a new ActionScript only project, click in the mainclass and type
autocompletion doesn't popup.
if I import TextField manually and then type
var asdf:TextField = new TextField();
again nothing happens.
Can you please attach the workspace log. It can be found in <workspace location>/.metadata/.log.
Also are you using an old workspace, created by FB4? If yes, try creating a new workspace and see if it happens.
Are you using 'Flash Builder Burrito Preview'? You might have faced this known issue https://bugs.adobe.com/jira/browse/FB-28451 . This is fixed in future builds of Flash Builder.
Workaround is, Click 'Restore defaults' in Preferences->Flash Builder->Editors->ActionScript Code->Content Assist Cycling
Or Changing workspace.
Let us know if this workaround solves the issue.
yap, that did do the trick!