Thanks for the update Frank.
I have used/tested many of the different model keys and capsules, but not specifically the "99" series, so I just took a set of keys and capsules from inventory, and installed them with little effort and no problems. The keys/capsules all snapped snugly into place by pushing down on the top of the keys. From the photo you attached of the key/capsule on it's side, I can see the capsule is fully/correctly inserted into the key, locking tab looks good, and the small plastic point is present on the locking tab (this hooks into the slot in the cartridge carriage, locking it into place). I tested "79" keys due to the printer model we have available to test with, but I also compared the "79" and "99" keys, which are exactly the same shape/size/mold, but use different chips.
I have attached a few photos showing an individual position installed in the cartridge carriage, so you can see the exit port is fully over the point in the cartridge carriage, and locking tab secured in the notch.
Since I don't have the exact same printer model you're using, if you continue having difficulty, please remove the keys/capsules and send me a few photos showing the inside of your cartridge carriage, then another photo showing one installed (like my photos below).
As I said, this is the first I've heard of this issue and we have many people happily printing with the "99" series capsules/keys, so we know they work well, and are confident we can get this sorted out for you.
Best regards~ Dana