As I've seen on its official website, Turbo HDD is released in a couple of versions (10 versions) for different brands. I've looked it up on the web to see exactly what is the brand of your HDD and it appears that it has been manufactured by Transcend.
On the website of Turbo HDD, there is no version compatible with the Transcend brand, therefore this could be the cause to your issues.
Also, the app might see the HDD temporary and then goes back to not detecting it at all.
I suggest to get back with developers to ask them if there is a version on that page compatible with Transcend HDDs.
Use the following link: http://www.gotofnet.com/ANSI/link.php?filename=fnet/contact/index.htm