It doesn't lock... it just appears to do so because the player has no idea what to do expect wiggle the mouse about until... well, something happens. There's no indication of progress, or getting in the right places. Sure, the tongue later works to indicate when you're in the right areas but the hands do not. I don;t know whether to click or hold or any particular movement. That's the problem.
Its the same problem with the player edging game. Until I saw the forum posts on f95zone.to of what to do, I thought it had hung. You added instructions for oral.
PS many images are not loading (eg belt spanking) because its still looking for .png files - well done for converting them all to webp BTW, notepad++ or similar will let you search the scripts to find the ones you missed.