Hello @mebesoco, looks like you encountered https://github.com/ValveSoftware/steam-for-linux/issues/5901 as a side effect of "Fixed an issue with invalid Steam Play tool selections if user had previously opted in to enable Steam Play for all titles. (Note: this will cause a one-time reset of all Steam Play global and per-app selections to the default state)." from the 2019-01-18 Steam client beta update, which went into the stable client release.
Closing in favor of the existing report.
After the most recent steam client update for the ubuntu 18.04 client my option to enable steam play for all games was unchecked and a game I had installed and had been playing was uninstalled. I'll grab my system information later today when I'm on that machine again and add a link to a gist with that information.