I have the original V1 Kickstarter, and the same loading problems discussed here, which seem to be sporadic, in my case.
I currently have 11 different PAL and Schick razors, and blades of all sorts, and I've spent a good bit of time trying to work out why a clean load isn't always happening. These are my observations, and I stand to be corrected on anything hereafter.
After trying the various razors and trying to assess such things as the different "closing" pressures i.e. the "bite-down" on the blade in each, it looks very much to me that the pressure with which the SE clamps the blade is somewhat less than with the older razors. The former relies on the central screw and spring to pull the parts up tight, whilst the latter seem to have a tighter clamping action along the width of the head. One test I've done is to put a fingernail into the injector gap and try to separate the top and bottom. This is almost impossible with the old razors (bar one), but pretty effortless with the SE. I appreciate that the V1 has the "problem" of excessive movement in the lower plate, but whatever the remedy applied to the V2, I would expect it to be less tight than the old razors.
I think that if the old blade isn't really held very firmly, and there isn't a consistent clamping force all along the head, then the new blade isn't held down very firmly as it enters the head, with the result that it will tend to push open the head halves and try to force itself up over the end of the old blade in this process. If the two ends of the old blades don't butt up exactly one to the other, then this becomes even more likely. I guess this is why the anticlockwise pressure described by
@globalm has the effect of counteracting the ride-over and lifting.
I mentioned that there is one old razor I have where it is possible to prise it apart quite easily (possibly a result of wrongly using twin blades in the past) and I can reproduce the injection problem about 8 times in 10.
The SE scores by having the removable different plates, and it seems to me it would be difficult to achieve a really tight clamping with the screw and spiral spring. I suppose the spring strength could be increased, but I'm not sure it would make much difference.
I should add that I am delighted by the performance of my Supply Provision V1 razor, and I don't find the alternative loading methods irksome. In fact, in some ways I like it better than the correctly-functioning older injectors, where considerable force is sometimes needed to eject/inject a blade, because they are held so tight.