There is a known issue for .mp3 files where some DJ softwares consider the file header to be ‘audio’, causing a 26ms misalignment in their beatgrid. This causes some DJ database converters to have shifted beatgrids. For more info: DJ collection converters - DJ Knowledge Base
However, I don’t think this is the problem we have with EP. It seems that EP is doing it’s own beatgrid analysis on all tracks and completely ignores the Rekordbox/Traktor/etc beatgrids when loading tracks from those collections. I believe this is the cause because the ‘grid’ column is empty when viewing any collection. ‘grid’ becomes once the track is analyzed or loaded onto a deck. This means EP generates it’s own beatgrid from scratch. If it was using the Rekordbox/Traktor/etc grid, then that column would have been checked once you imported the Rekordbox/Traktor/etc collection.
Example: here is a playlist from my Traktor collection (which I synced/updated) which I imported into EP. I loaded track 10 onto a deck which took 1-2 seconds as EP generated the beatgrid. All other tracks have the ‘grid’ column empty, even though they have been gridded in Traktor. Interestingly enough, EP seems to import the key and cue points… but not the grid…
To further my suspicion that EP doesn’t import external grids: the EP manual has been updated between version 2.2.0 and 3.4.0: all mentions of importing beatgrids from Traktor/Rekordbox/etc have been scrubbed. Beatgrid import incorrect for Traktor or Rekordbox - #7 by Akuro This is extremely frustrating to me as all the marketing and documentation lead me to believe importing beatgrids from Traktor/Rekordbox/etc. was supported. Yet, Dennon seemed to admit this wasn’t the case… and haven’t added the functionality since. Meanwhile, all of us who thought Dennon would be an affordable alternative to Pioneer, still have thousands of tracks gridded in Rekordbox/Traktor/etc. Redoing every single beatgrid (even if EP beatgrid analysis was PERFECT) is simply not a realistic option. And paying for a subscription service to convert between formats causes things to become pricier again lol.