I use CTI hardware with Aeropack retainers all the time, so something is wrong with your individual setup. It could be any of three different things, or a combination of things:
1. Problems with the CTI hardware - measure it or try a different set,
2. Problems with the Aeropack - measure it per rfjustin’s suggestion,
3. You have an issue with the motor mount tube (MMT). This is by far the most common issue I’ve seen. In fact I’ve never seen an issue with #1 or #2 above, but that doesn’t mean it can’t happen. Just one drip of epoxy in the MMT can make it seem as though there are problems with the hardware. I don’t ever epoxy on the retainer without test fitting the motor hardware first, and I usually have the motor in place when I epoxy the retainer to the MMT just to prevent getting it off center. Fortunately, if it is a problem with the motor mount tube, it’s more easily rectified. Just scrape out whatever is interfering.
Edit: disregard #3; I see that you are test fitting without the MMT installed. You definitely have a problem with either 1 or 2. Do you have another motor to test fit?