What is this Transcend device?
An SD card? A SSD drive? A USB flash memory 'stick'? An external USB hard drive?
And where are the originals - still on the SD card in camera? If they are still on the SD card, just start the import process again.
Quote: I generally transfer my files from my Memory SD card to my external hard drive using Lightroom
What is your workflow like? Is it:
- remove SD card(s) from camera;
- insert SD card into card reader on PC;
- start Lightroom;
- import images via Lightroom from SD card to external drive, converting to DNG along the way
- replace SD card(s) in camera
I suggest using a different workflow:
- remove SD card(s) from camera;
- insert SD card into card reader on PC;
- using Windows Explorer, copy image files from SD card to external disk
- open Lightroom, import files from external disk location, do any on-import conversions necessary;
That way you aren't relying on Lightroom to do any copying and file transferring.
Oh, and I'd set the camera to shoot DNG in the first place, rather than ask Lightroom to do it on import.