If all else fails, you can skip the Observatory entirely. This requires downloading a save editor or a pre-made checkpoint.
SaveSlot1.sav with the downloaded file. Back up your original first.Sometimes the bug is caused by a corrupted shader file preventing the cutscene from loading. prince of persia the forgotten sands the observatory bug fix
Many players instinctively hold down the interact button (or the movement key) while rotating the dial. In this bugged state, the game sometimes ignores a "held" input. If all else fails, you can skip the Observatory entirely
Try this instead:
To avoid getting stuck in similar situations later in the game: Replace your SaveSlot1