I have had same problem....which is pain in 100 degree weather after pumping up the tube.
when I put new tubes on I tighten the core, often not super tight from factory
I carry a park core tool on the bike and double check before pumping
and as much as I liked the lezyne, I got a Silca Tattico pump....it is even better and has press on fit with lock lever and flexible hose
__________________
Life is too short not to ride the best bike you have, as much as you can.