Can't see certain users when importing tweets with keywords

 When I use SuperMetrcis to import tweets containing a certain keyword (in this case MM17NL) a get a nice list, but some users are missing, mainly my own @guido account. For example: this tweet https://twitter.com/guido/status/831961174904336384 should show up, but it doesn't. Also when I sarch on twitter for the keyword https://twitter.com/search?q=MM17NL&src=typd the @guido account doesn't show up.

Could it be that my account is somehow blocked from Twitter searches? How do I find out why this is happening?