I have come across a bizzare problem. I originally made a very simple database back in the early 2000s using (probably) FileMaker 7 for Windows. I scarcely ever used the database but converted it nevertheless with each successive version of FileMaker. I now use FileMaker Pro Advanced 17 on a Mac at home and on Windows at work. The file lives in OneDrive so that I can access it either place. Recently I dusted this database off and decided to use it again - it is a simple task list. Spruced up the themes made a few changes to fields (added a few and deleted a few) - nothing major. I also deleted all data and then started entering new data. A week or so later I has cause to delete a record. I used the Delete Record button on the tool bar. It gave me the normal Are You Sure You Want to Delete message and I hit yes. It promptly deleted ALL records. I couldn't believe it and tried saving a copy, closing and opening FileMaker to no avail. The data was gone. I then made a copy in the hope the data would miraculously return - no luck. The next day on the Windows machine I opened the original file and there was my data which I promptly saved. However to ensure I had not accidentally somehow asked it to Delete All Records I set about testing it by entering dummy data and hitting Delete Record. Every time it deletes ALL records. I have tried saving copies of the file, building clones of the file and even creating a brand new file into which I copied the layouts and scripts - rebuilding fields) but to no avail. I also tried finding a specific record so that there was only one record found before deleting but to no avail. Every time I hit Delete Record it deletes ALL records. Never ever encountered what is clearly a corruption of some sort in the file in this way. I also tried recovering various editions of the file to no avail - FileMaker said it recovered the file just fine - no errors. Has anyone encountered this before?