I just got back to the MechFlower and here's what I found... The problem seems to be only with the autosave file. I saved in Dinah just before the MechFlower scene, then saved (my own save) at the start of the MechFlower scene and played it through without quitting during the scene. I saved again just after that scene.
Then I quit and restored all my saved game files and had no problems with any of them. The Autosave at the MechFlower had disappeared by then, so I restored to Dinah and played to that scene again. I then loaded one of my other game files, followed by loading the MechFlower autosave and it played fine. So, I quit the game, then started it up again and tried to play the MechFlower autosave and it would not play - I can move the characters, but they won't interact with anything and only the tabs will switch the characters, not clicking on them. This only happened on the autosave and after I quit the game then restarted it. All other saves are fine, including my own MechFlower save. Just the autosave acts up and only in the MechFlower scene.