LBV Harnesses and Grenadier harnesses of every camo pattern and the raven vest show a units heat through thermally insulating suits like Viper Uniform or CTRG Stealth suit. The pockets and pouches don't show heat just the strap or body of the vest. I do not believe this is an intended feature as every other vest in the game, even the thin ones like chestrigs show up cold on FLIR.