Release of drivers for Bootcamp is controlled by Apple. If you are dissatisfied with the time table in which they are making driver updates available for their product you should let Apple know. These forums are USER to USER forums only, not AMD employees so none of us can help with driver updates beyond advice on how to install existing drivers with mostly Windows based setups, excluding MAC. Apple provides their own support for Bootcamp. If you need to contact AMD you can do that from the contact page on the main AMD website.
Apple have to request a driver update from AMD before AMD go about testing a newer version for Macs.
If enough people complain to Apple then they will request another driver update if it is unusable for you.
There is an unofficial route also at www.bootcampdrivers.com which is the website I run.
18.8.2 works well on Vega 64 but doesn't work at all on Vega 56. The last working version WAS 18.5.2 until the latest Windows update broke it.
Now a workaround method for 18.3.4 is the last known working version for Vega 56.
18.9.1 has not been tested yet for iMac Pro though I will be releasing Alpha status drivers in my forum for willing volunteers to test today.
Thanks for your answer. My iMac Pro is my main computer for my daily 3D work and I'm affraid that I damage more than I gain with bootcampdrivers.com. I'm afraid that if this is not working my PC needs to reconfigured again