This doesn't appear to be a Twitter issue. It's a Yootheme issue.
I have Joomla 3 (new install) with Yoo_Catalyst and Widgetkit 1.3.1
I enter a single twitter username in the settings, with no @symbol in front
I clear the entire cache, not in Joomla, but by logging in to backend server, and clearing entire contents of cache directory.
<CTRL+F5> on the home page to force complete rebuild.
Check the cache again; this is what I see;
Widgetkit has spawned and interacted with Twitter.
I see GALLERY directory, I see TWITTER Directory, a widgetkit js and css file. Now I check the TWITTER directory.....
I have a nice freshly minted PHP page which contains, guess what?
5 lovely new tweets from the chosen user!!!!!
NOTHING APPEARS in the FRONT-END of the site! The module remains BLANK. So, I change module publishing position from SIDEBAR-A to the FOOTER; as a test; and what do I see?
NOTHING - module doesn't appear at all; let alone its title and blank real-estate as in the SIDEBAR position;
One more try - this time publishing to ABSOLUTE;
NOTHING DISPLAYS at all; not even module title (expected?);
One last attempt, this time TOP-A
NOTHING DISPLAYS; I do see the module TITLE; but zero content.
Hang on; let's check that cache again?
Oh, what do I see?
All the cached content is there (truncated above to protect the innocent).
So? What gives Yootheme team? Your stuff is normally so good. Your code is obviously grabbing the content for the module but is struggling to show anything. I note a bunch of errors in my httpd error_log saying "cannot find personal.css". Could this be associated? I cannot tell which yootheme element is trying to call this CSS so can only guess!