Almost 8 months later, problem still exists in Chrome 76 dev channel. As long as I don’t reboot, I can reopen the app indefinitely while staying logged in. Killing the process doesn’t matter. However, as soon as I reboot the system, I have to login again. Same problem with the Google login and a normal email account. Web version works fine between reboots.
I really want this issue fixed, so if you need any info, literally anything, please ask and I will happily help you debug this. I also have an old Chromebook where I can test different channels.