From Tamron:
Dear users and potential purchasers of Tamron interchangeable lenses.
Thank you for using Tamron products and for your continuous support.
We would like to announce that we have discovered issues that some of Tamron Di/Di II series for Nikon mount models may not operate properly on Nikon Z7, which was newly released on September 28, 2018, with Nikon Mount Adapter FTZ.
We are investigating the causes and will make further announcement of the compatibility for every single model once we find the solution.