Well, the US is big, so only big bins are appropriate.
Jokes aside, the CT Mini is really an "installer's vac" and even at that it makes sense mostly if one needs to be carying it up flights of stairs in an appartment block without lift(s). Not something very common in US but quite common in Europe .. so most likely it just did not sell.
Further, in Europe, the Mini is commonly sold as a household vac (you need small bin, as big one means organics will smell for staing too long in it in an average household). This again uplifts the sales disproportionately compared to the US.
And, again, it is very specific and only because household vacs are law-limited to meager 700W in Europe ... while the restriction does not apply for industrial DEs.
Best is probably to offload the Mini bottom of someone in US and give them your new Midi one. I am sure there are folks who will be up for a swap.
Also, it is possible to order the mall bin as a spare part.