To anyone else having this issue:
I have managed to fix the problem on my MSI GP73 Leopard 8RE by updating the GPU's vBIOS.
The issue was exactly as described earlier, the Vive Pro's display would either not be detected at all or report a HDCP error around 30 seconds after starting up. After downgrading the nvidia drivers to or past 417.77 the headset worked as expected.
I have contacted MSI support on this issue, whom I must say were very quick and helpful with resolving it. They have instructed me to fist update my machine's BIOS and then the GPU's vBIOS firmware (from v. GTX1060_86.06.60.00.25 to GTX1060_86.06.60.00.42). Please note that the vBIOS update is not available on the MSI website, so you probably have to ask support for it as well.
After updating the vBIOS to GTX1060_86.06.60.00.42 and updating to the latest nvidia drivers (442.19) the Vive Pro works as expected.
