I was having the 'unlicensed vehicle ' issue too. Tried re-sync'ing but to no improvement. Read several threads and saw something, so I tried it. It worked.
My normal car is a 3 bar Speed density turbo'd 5.3 in a 96 z28. I've been using HPT on it since 2015 or so.
My friends car is a 1 bar stock type 5.3 in a 1980 Trans/Am. I put the engine together and installed it for her. I bought 2 credits for this tune and it could pull the current tune and I could modify/save it but could not upload. It would simply say, "Unlicensed Vehicle" and never presented the option(s) to license the new PCM or to use the credits, etc. So in the article, it mentioned
( a ) copy the lastest application key for HPtuners (highlight, CTRL + C)
( b ) Hook up your dongle (HPTuner device) to your laptop using the USB, doesn't need to be attached to the vehicle at this point.
( c ) Open the editor, click 'Help', then click 'MPVI' application Keys.
( d ) A drop down box appears where , towards the bottom, your current Interface ID and Application Key. To the left of that is a reddish in color fat minus sign. When you click on the Minus sign, it deletes the Interface ID/Application.
( e ) paste in the application key you copied on step ' a ', then click 'Add Key'.
( f ) exit.
After I did that, I took my laptop and harness/dongle out the the T/A, hooked it up, turned on the key, made sure the scanner still worked/read, the went to the editor and clicked 'write'. NOW the license dialog popped up and I was able to select the write. I had to take the option to 'write entire' to go forward but I got it uploaded. Afterwards, cycled the key, started the scanner, cranked her up and she fired up right off the bat.