I have encountered this annoying behaviour of Keyshot 5 sometimes not opening when I start it within Keyshot ST8. It just stays in the initializing state and does nothing until I have to force-shut it.
Usually restarting my system helps and the first time I try to open Keyshot it usually opens just fine, but sometimes after the first time it fails to open. No matter if it is assembly or a part, sometimes it fails and sometimes works, even for the same exact part or assembly.
I just upgraded my workstation to Dell Precision 7510, i7-6820HQ, Quadro M2000M, 16Gb RAM, Windows 10 and have the latest MP8 for SE ST8.
Any ideas how to fix this?
I have seen this behavoiur last week too.
Always I startet an assembly the first time, no problem occured.
Closing KeyShot then, going back to SE and opening KeyShot again - no matter wether this ASM or another one - the KS startscreen hangs.
Kill it with task manager, closing SE and restart it doesn't change anything.
Only a reboot helped to do it once again.
I updated Keyshot to the latest version (Keyshot 6) from their website. Now it works like a charm again!
Maybe you should try to do the same.