So I just entered a new title into ComicBase 2020, and I entered some title specific data. Then I realized that I has it classified incorrectly (I entered it as a book when it should have been a comic). So I selected Edit > Change Title Media Type and selected Comic. This process took a couple minutes to complete. When it was done, I then added additional issue data. (I noticed that the cover date field was blank, when I know that I entered a date when I had this item stored as a book.) Then I selected the previous title using the left arrow in the top right of the screen, and I was then given an error stating "It looks like there's an invalid date that snuck into one of the date fields for this title. Fix it now?". I selected no, closed the application and restarted it, and I was still getting the same error whenever I tried to navigate to a title. (However, the original title that I had entered that started this problem still displayed correctly.) Finally, I selected "Yes" to fix the data. The process took about 10-13 minutes. I then went to enter another issue, when I noticed that ALL of my data from ALL the custom fields was gone. I assume that this happened during the "fix". I made a backup of the database before I fixed it, but it's useless as I can't navigate to any titles. When I open the backup, I get an unhandled exception error "String was not recognized as a valid Date Time". I can continue past the error, but I continue to get the "invalid date snuck in" error.
Please don't tell me that my data in the custom fields is lost.
Let me know if you need any additional information.