LatestTweetOf should be as in custom search i don't find any LatestTweetsOf at build stage 1. Okay.
So, i have repliacated your issue again and i set
RecentTweetsOf - double click - set value 4
Outside - Maxiitem = 4
Result : The bot tweeted latest tweet of that target profile.
I have run the action and it gave old tweets and it seems the action is working only 1 time.
Your issue ahs been reported to martin with explanation. Please wait fort he reply from martin.