Hello everyone, this is Troubleshooter development team.
We received the report about the issue that our game is being displayed as not-purchased state and you can't play the game anymore.
The development team made the official complaint to Steam about this issue.
Developing the game is responsible for the team but this issue is about to Steam system so there is a visible limit for us to help you.
We will use every method to contact to the Steam to solve this issue.
Thank you.
** Update **
Our user has suggested below guide.
Go to Steam Settings → Downloads → Run [ CLEAR DOWNLOAD CACHE ] → Restart Steam
I would like to recommend you to follow above steps before Steam solves this issue officially.
Thank you.