When I go to video is shows QSV auto selected at the bottom of the box you show, my GPU selection is AMD480RX. Both work when I render as seen in task manger. Got to be something in your system. i7700/4200 hz, 32 gig, AMD 480RS 8 Gig, MSI motherboard, windows 10 PRO.
@vaddd What is your CPU? It may have Intel QSV. However, it if's more than 5 years old it may not be supported by Vegas any longer. Please take a look at device manager and see what it says for graphics adapters. Then in Vegas 18 under help, click check for driver updates and update the graphics driver if you aren't on the latest.
I do recommend Intel QSV decoding- according to Magix it's compatible with decoding the most types of media. While performance is less than my NVIDIA decoder, Intel has been rock solid (I stupidly changed it from the default of Intel using VP 17 and was plagued with freezes until NVIDIA fixed its drivers this spring).
@vaddd: We have added a new feature to detect the available/usable hardware decoders in VP18. This was not the case for VP17, where we listed all decoders VEGAS supported, regardless of whether those were available on the installed PC. It also meant that you could select a decoder, but not be sure whether it was actually being used (VEGAS would default to a software decoder if it could not find the selected hardware decoder). Do note that this feature works in conjunction with so4compoundplug, so enabling the legacy AVC decoder will not show these (as the older compoundplug does not use any kind of hardware decoding).
The fact that you can see AMD UVD when the legacy AVC decoder is unchecked indicates that VP18 is only able to detect the AMD GPU, and not the Intel integrated GPU (I assume you do have a Intel CPU with QSV support). Please check if your Intel drivers are up to date by going to "Heko" -> "Check for Driver Updates". Because of the constant updates which occur with Windows 10, and the GPU drivers themselves, we do need upto date drivers to take advantage of hardware decoding.