External HDD keeps prompting to format drive while Recuva restores files

I'm trying to recovery files from a Windows laptop's hard drive that stopped booting up. I'm using a Siig Cool Dual SATA to USB 2.0 Docking to connect to the drive, and when it connects, I get prompted to format the drive. I clicked "cancel" then open the command line and run "chkdsk g:/f/r and see that the drive is NTFS, and get a message that says it ran successfully (I'll post a screenshot of the message when I get home later today). Side note: When using Windows Explore to navigate on this drive, no files are found - I only see files after Recuva scans the drive.

I'm using the free version of Recuva, and after running a scan it finds 100k+ recoverable files. I run the recover files option and save them to a separate external hard drive, but while files are being recovered, at some point I get prompted to format the problematic drive again. When this happens, the file restoration process terminates, and I have to start all over. I do see some recovered files that were saved to the separate external HD, so the recovery process does work; as I stated it just prematurely terminates when I prompted to format the drive again.

Is anyone else experiencing this? What is the solution? Any help would be appreciated, thanks.