I set a couple of keyframes on the timeline. Scrubbing works. Playback works. However, when I close and re-open the project, it no longer works. Is this normal?

I downloaded the latest nvidia driver and houdini daily build, thinking it might be an issue. However, I get the same result. Here is the hip file (very simple). Again, when I first created it, scrubbing the timeline showed the procedural noise anim. I see the positions in the color ramp animate, but I see nothing in the viewport change.

looks to be a bug - you can submit via the Support menu above.

A temporary fix is to just re-e=enter the first keyframe value and press enter, or, click ‘Force Compile’

Was there a bug logged for this? In anycase, this is now fixed for tomorrow's daily build, Houdini 16.0.561. This issue only affected ramp parameters on VEX/VOP related nodes.

Yes, a bug for it was logged and referenced this post as a description of the problem.