We’ve had this happen a few times with our characters as well, and it’s pretty annoying. What I ended up doing that seems to have fixed it for the time being is to recreate our child pawns by right clicking the parent and selecting create child from blueprint. Our other characters were originally made by duplicating, then setting the parent manually under Class Settings a while back, on 4.6. We didn’t have much functionality then, so it wasn’t a problem, and for a while we assumed it was something that broke when we upgraded from 4.7 to 4.8, as we jumped right onto the preview builds rather than wait for the official release.
Since recreating our blueprints this way the only time we’ve encountered the issue is when a parent class is updated and compiled, the child class gets updated, but is then reverted. A quick fix that worked for us, and may for you, is to make a change to the parent that requires it to be recompiled. When we did that the proper values propagated down to the children and both assets, once saved, retained those values on restart.