Aha. Resumed at the save. The platform across raising up is the problem. The activated levers won't 're-activate'. You can't turn it either way. The platforms over the gears between the sliding panels now get bugged and make you fall unless you can jump over the window in slow-mo to get back to entrance. But yeah. No platform across means no moving ahead. You can jump on the platform while jumping poles but get no farther again. It's not exactly what you would call getting 'lost'. The path is well set and known. It's just darn inaccessible.
I think this game had potential to be more open ended and more big. I think they should have made the whole game re-accessible to the Sandwraithe part as well. Would have been fun. The only drawback has been you can't travel back top the Sandwraithe levels as the prince later. There is no absolutely no path that you can access to any of those areas once you are back as the Prince.