The program won't accept them at all anymore. What changed?
Similar was mentioned in the 1040 20.15 beta "bug reports"
https://forums.garmin.com/beta-program/edge-1040-series/public-beta-bug-reports/i/edge-1040-series---20-xx-bug-reports/20-15-change-of-lap-information-in-fit-file-causes-troubles-if-imported-to-other-apps
Seems to be a permanent change?
