I've been having this issue for a while now. Whenever the pan law is set to the default mode in project settings, all automation I create in the pan/width lanes becomes invisible upon closing/re-opening the lane. I have tried this with other automation lanes, and it ONLY happens with the pan and width lanes. Volume, mute, sends, and plugin effects all respond normally when I automate them. I thought it may have something to do with the pan law, but no matter which mode I try it always gives me the same problem. I've attached a video proving my claim:
https://www.youtube.com/watch?v=b-vq3Gtscko
Notice that the pan pot adjusts correctly when I change the automation. So, the automation is being taken into account by reaper, but it is not visually accessible. This is extremely frustrating whenever I want to do any kind of panning effects! >=(