I take it this is actually the Tamron 150-600mm zoom lens? Since as far as I know, backed up with a quick Google search, Tamron do not make a 600mm prime lens. If it is the Tamron 150-600 is it the original G1 version, or the newly released updated G2? I rented the original G1 not long after it first came out, and coupled with my 50D it reports correctly and without issue in LR, in both LR 4.4, which I was using back when I rented it, and now with the latest version of LR CC 2015. In the end I went with the Sigma 150-600 C, because the OS system in the Sigma works while panning. The Tamron firmware fix for the G1 solved the VC feedback issue by simply turning the VC off automatically when it detected panning. What is of note to this situation is that while LR, again both V4.4 and CC 2015 both correctly identify the Sigma lens too, when uploading images to POTN, AMASS identifies the lens as a Canon 100-400 IS L II. Perversely AMASS manages to get the set focal length correctly, so in the lens sample thread, where people don't manually correct things, you will se the lens listed as Canon 100-400mm @ 600mm
Alan