I'm no expert by any stretch of the imagination, but I would tend to rule out magazine problems at this stage. Primarily, I find it difficult to accept that 8-10 magazines of different vintages would all give the same problem, especially after such limited use. Also, the OP's trial with alternative magazines did not solve appear to solve the problem.
It does seem logical to conclude that the rounds are sitting too low in the frame. This could be caused by a number of factors, such as out of spec parts or manufacturing.
There are a few ways to address this problem. The OP could buy new magazines, which are designed to sit higher in the frame. The problem with this solution is that the gun will only work reliably when using these magazines; the OP would not be able to use a standard magazine.
While I think that upgrading the internals of the magazines would be worthwhile at some stage, I think that it is unlikely to solve this particular problem. If the problem was caused by weak magazine springs, then the problem is unlikely to resolve itself after the first few rounds have been fired from each magazine, when the spring tension has been reduced further.
I suspect that the EGW magazine catch may be the optimum solution, once correctly fitted. This will cause rounds to sit higher within the frame while still allowing the use of most magazines.
That's where I would start, anyway. Others may and will disagree