Well, this might be the answer we've been looking for. Variety has a story detailing the issues that The Dark Tower movie has run into. It's an interesting read, but the detail that sticks out the most is that three separate entities apparently had some form of veto power over the film.
Variety has sources detailing clashes between director Nikolaj Arcel, Sony Pictures and Media Rights Capital (MRC). But there's also the interesting fact that all three are united in saying that there were no real problems, and that every stumbling block was just the result of normal growing pains for a big fantasy movie.
There have been a lot of questions about The Dark Tower, including why the running time is so short and why we haven't seen more promotion of it. The answer to the former may be that test screenings reportedly showed that viewers couldn't understand the story, so perhaps it's been streamlined. The answer to the latter is probably in this bit of the Variety article:
Sources paint a more acrimonious picture of the production, one that was enabled by the unique nature of the deal that Sony struck with MRC — a pact that allowed competing power centres to emerge. The two companies split costs, and in return MRC was granted "kill rights" on everything from the marketing campaign to the final cut of the picture. If one company didn't like a trailer or a cut of the film, it had to be scrapped, making it difficult to achieve consensus. It's a rare type of partnership, with the kind of sign-off that few production companies enjoy. That led to a case of "too many cooks in the kitchen," according to one insider. [Stephen] King also had a great deal of input. In return for the rights to his work, he retained veto approval of almost every aspect of the film.
That means Sony made a movie that MRC and author King both had veto power over. And Sony could object to any decision MRC made. It's no longer surprising that it took so long to get trailers and other marketing for this movie — it's apparently a miracle that we got any. The movie could be good, we don't know yet, but this definitely sounds too many cooks; even if they get there in the end, there is no way this was smooth sailing.
We reached out to Sony but had not heard back at time of writing.