Thanks for the suggestion Wendy, I couldn't get C:\Program Files\NVIDIA Corporation\Ansel\Tools\nvCameraEnable.exe whitelisting-everything to fix the problem.
It appears to be a problem with GeForce Experience 3.18, since when I revert back to GeForce Experience 3.17 I can use Ansel in Flowscape again. It looks like in GeForce Experience 3.18 one of the updates is that Ansel RTX comes out of beta and that may be causing the problem.