I experienced the same issue with Vittoria latex tubes. I wore out the Michelin Power 25mm clinchers that I ran last year and switched to Challenge Criterium 25mm Open tubulars that I got at a good price. I reused the old latex tubes (eventually) but had to run the tire with a butyl tube for one ride to get the new tires to conform to the rim and relax a bit. Then I removed one bead, removed the butyl tube then re-installed the latex tube very carefully. The latex tube did have several folds in it which I got reuduced down to one small fold by deflating, applying talc, partly reinflating, then mounting the bead, inflating to about 50 psi or until I heard a noise, deflating one more time then finally inflating up to full ride pressure. No pinch flats yet doing it this way but I’ll admit it is quite fussy.