Yesterday, from Donald Trump (r), via Twitter:

Donald J. Trump ‏@realDonaldTrump
Why haven’t they released the final Missouri victory for us yet? Could it be because Cruz’s guy runs Missouri? 8:53 PM – 18 Mar 2016

Could it be this?:

State of Missouri – Presidential Preference Primary – March 15, 2016
Unofficial Results
as of 3/19/2016 9:57:57 AM

U.S. President 3041 of 3041 Precincts Reported
[….]
Chris Christie Republican 1,677 0.179%
Jeb Bush Republican 3,349 0.358%
Ben Carson Republican 8,201 0.876%
Donald J. Trump Republican 382,093 40.831%
Marco Rubio Republican 57,006 6.092%
Ted Cruz Republican 380,367 40.646%
Rick Santorum Republican 729 0.078%
Carly Fiorina Republican 613 0.066%
John R. Kasich Republican 94,533 10.102%
Rand Paul Republican 1,771 0.189%
Jim Lynch Republican 102 0.011%
Mike Huckabee Republican 2,137 0.228%
Uncommitted Republican 3,216 0.344%
Party Total: 935,794
[….]

[emphasis added]

And this?:

Missouri Revised Statutes
Chapter 115
Election Authorities and Conduct of Elections

115.508. Notwithstanding any other provision of law to the contrary, no election authority or verification board shall certify election results, as required under section 115.507, before noon on the Friday after election day.

Political amateurs have no understanding of the concept of election certification. Political professionals and media long ago sacrificed that concept on the altar of instant results.

Or it could be short attention spans. Look over there! Squirrel!