-the short term solution-
1. take your affected capsule. set it on its un-punctured/un-perforated bottom (the thin foil surface) on a flat surface. the three puncture holes should be facing upward on the top of the capsule. by the way, if you shake the capsule you should hear the grounds sound dry as if the capsule was new.

2. find a thin small rubber band. size-wise, ideally, the rubber band will fit loosely around your thumb; with a very small gap between the rubber and your thumb.

3. put the rubber band around the collar of the capsule. the band should be put over the top of the capsule and pushed down until it stops flush against the flange (rim). if the band is correctly placed, the band will be just 1mm flat inside the rolled bare aluminum edge (rim).

4. insert the capsule in your citiz machine as usual. optional: you can orient one of the puncture holes at 12 o'clock position (top dead center) during the insertion process. this time, it will work. you will find the capsule will eject cleanly with the rubber band intact.

5. save the rubber band.


-which machines does this apply to?-
this is a common problem with nespresso machines introduced after 2010, specifically the citiz. i have not seen this problem on the pixie, yet. i would expect this issue on the lattissima plus.
i am assuming that the machine is otherwise functioning properly: meaning that the machine does not have an issue with the water pump, excessive scaling deposits restricting water flow, or some other major mechanical part.
-why is this happening?-
look at the capsule, the post-2010 machines bite new slightly rectangular indentations on the capsule around the top edge of the wall. this is new. nepresso changed the insertion mechanism in response to competitors bringing non-nespresso branded capsules to market: Douwe Egberts/Sara Lee "L'or expressO", Caffe Vergnana "ESPRESSO", etc.
this new insertion mechanism was supposed to thwart knockoff capsules, instead it is unintentionally thwarting your "real" nespresso capsule. the injector needles are not piercing correctly all the way. the injectors poorly lodge: deep enough to make puncture holes but not deep enough to allow water to flow freely into the espresso grounds compartment.
two things can happen:
1. the pressure release valve, inside the brewing chamber which prevents an explosion occurring if the coffee exhaust path becomes blocked, is activated and hot water overflows into your used capsule basket.
2. the hot water flows outside and around the capsule and into your cup as clear hot water.
-what do i do long term?-
contact nepresso. get your machine repaired or replaced. this is a factory manufacturing defect that has nothing to do with you, wear, use, or hard water. refuse to pay the $125 repair fee. demand that they fix the machine free of charge. they will send you a loaner in a plastic shipping crate to use while your is being fixed. you should not have to suffer without espresso or waste legitimately purchased capsules just because nespresso is in a legal fight capsule copycats. this is not your fault.