Folders spontaneously emptied out Drobo 5N2

Hello, I am really alarmed to have discovered three folders with hundreds of files completely emptied out of their contents. This was certainly not done either deliberately or accidentally and appears to have occurred completely spontaneously. One smaller folder appeared empty on Drobo, 0 items, yet when copied to a hard drive the files appear. Yet no such luck with the other two folders with the most critical data. All three drives appear completely healthy, all green lights. What can I do, how can I recover the data? Will Disk Warrior help? The device is out of warranty and DroboHelp is seemingly not available in Europe.
thank you