i'm also not a big fan of the extended capacity magazines. Again, just my opinion, but the standard size 365 holds enough and doesn't compromise concealment. At the last IDPA match I SO'd, I had to holler "Stop" twice for one individual shooting a 365 with extra capacity magazines for malfunctions that, I believe, were caused by the extra capacity magazines.
Never had a problem with OEM higher capacity magazines with the P365.
I question whether the magazine was the issue... particularly if he was running reloads.
Jerry