Switch back the Digitrax SoundLoader, do a factory reset and then re-address to 106 and the loco was found to operate correctly.? .? ??
So decoderpro IS programming the loco, just not to the address you are expecting.
What address does Soundloader claim the loco is set to BEFORE you do the reset?
Does the loco operate correctly if you then attempt to run it on the layout using that address?
It sounds to me like DecoderPro is setting it to Long Address 106, but you are setting it to short address 106 using Soundloader.