It's no secret that it took a lot of back and forths to get Star Trek: The Motion Picture greenlit. Originally, it was going to be a series [Phase II], but after Star Wars came out and was so successful at the box office, there was sudden interest in making a big screen Star Trek.
Academy Award winning director Robert Wise, who'd previously directed West Side Story and The Sound of Music, was chosen as the director, and this brought confusion to some of the parties involved. Although Jon Povill, the associate producer said "everyone was pretty much thrilled at the prospect of working with Robert Wise," Richard Taylor, who supervised the storyboarding for The Motion Picture, was also reported in The Fifty Year Mission The First Twenty-Five Years by Edward Gross and Mark A. Altman as saying "I don't think he was ever very enthusiastic at all about directing this movie." In Taylor's opinion, it was just a job to the 65-year-old director, but Wise had previously directed another sci-fi movie, The Andromeda Strain in 1971, which was a box office success.
Taylor went on to say that "he [Wise] was older and he would sit there on sets and drift off and then have a masseuse keeping him awake." And when The Motion Picture wasn't exactly what Paramount executives expected in terms of critical reception, Wise took the blame for the issues with the movie even though it was a hit at the box office.
Though some fans still have issues with The Motion Picture, it has, over the years, developed a following, especially once it was made available for streaming. No, it wasn't a perfect movie, but I doubt very much that a drowsy director caused all of the issues people claimed it had. For me, I enjoy the movie mainly because it was a return to the The Original Series and a chance to see the crew back in action again.