Is this the part on the right not clipping when you try to close it? I had this exact issue. Kind just jiggled the left part to change the angle then tried again. Eventually got it, but I wouldn’t say it was a perfect seal. I quickly pushed the silicone sleeve over it before it could detach. Prints came out fine.
My 2nd A1 Mini doesn’t have this issue, so it does seem like a possible defect. It’s such a small part that I could see it being a slight misalignment or something.