System : NUC8i7HVK with Radeon RX Vega M GL Graphics running windows 10 with 3 1080p monitors.
I have Eyefinity running in landscape fine but I cannot switch to portrait mode, how is this done in the settings?
First I would make sure your Intel has the latest Intel Drivers especially the Intel Graphics. Here is the last latest AMD Driver for your AMD GPU: Downloads for Intel® Core™ i7-8809G Processor with Radeon™ RX Vega M GH graphics (8M Cache, up to 4....
Intel latest Graphics for your computer: Download Intel® Graphics - Windows® 10 DCH Drivers
Intel Management Engine: Download Intel® Management Engine Consumer Driver for Windows® 10 64-bit for Intel® NUC
Intel's latest AMD Driver for your Vega M: Download Radeon™ RX Vega M Graphics
After updating to the latest Graphics for both your Intel and AMD GPUs, if you haven't done it yet.
Check if Eyefinity works in Portrait.
AMD drivers works best when you have the latest Intel Graphics driver installed.
In case you haven't read AMD Eyefinity guide here is the link: https://www.amd.com/en/support/kb/faq/dh-014