Greetings, all!
Just wanted to post this in case it might help someone in the future. I had a call for a 2016 328i to add a spare FOB, and I had a few renewed HUF5676 keys that I had renewed with VVDI Key Tool sitting in my van. On site, the FEM unlock went fine, the transponder programmed, but the FOBs (three of them) had no remote/comfort function. They all had good batteries, were sending the right signal, etc. I ended up flashing the FOBs again but this time with HexTag, then running the unlock process again, and I had no problem. Not sure if it was the unlock that was the problem or the FOBs (someone on another site mentioned that vehicles with updated ISTEP will not take the VVDI flashed keys), but AHII/HT got it done.