Just wanted to chime in on this issue as well, as I discovered last night I also had lost data within custom field #1, same field that Gary is using to track location/box. I only noticed it while doing some basic reporting reviews, and seen that some of the issues had my location field missing or blank. My installation of Comicbase 2020 was on a fresh Windows 10 install, with a copy of the 2017 database used as the imported data. I lost approximately 300-400 entries (from a 10,000+ collection), random issues, in random boxes there didn't seem to be a pattern for the ones that went m.i.a. Fortunately I still had an older copy of my database, under a previous version of Comicbase for reference. I was able to use it to look up each book, and re-key the missing data....but it was extremely time consuming. I just figured it was 'growing pains' with the new version.