Love my Solo III but can't seem to fit in all the included glass pieces

MAN, what an incredible device. I recently quit smoking tobacco and got this as an alternative. I had a POTV XMAX before and this is a whole another level, really smooth pulls that don't feel like you are sucking through a straw.

However, I can't seem to fit the included XL piece frosted glass piece for bubblers. It fits down to the edge of the metal tube but then doesn't budge, maybe .25 inches in. The other XL piece slides in perfectly.

Any ideas? I'm scared to force it in but twisting it and moving it around doesn't have any effect. Thanks!