Not according to the news...of course Montana delegates can change their mind but at this point 18 of them say their for Cruz!!!
I don’t find any news indicating the results you are saying. Here is a article from Fox
dated April 2, 2016.
Snip
Montana Republicans are asking the U.S. Supreme Court to step in as early as this week
and force the state to “close” its upcoming primary so only GOP voters can participate — in
a case that could pose complications for Donald Trump.
The Republican front-runner so far has done better in “open” primaries, where members
of both parties can vote, than in “closed” primaries limited to Republican voters only.
Montana, set to vote June 7, has had an “open primary” since 1912.
end snip