Apps in Android can't fully control when they get shut down. The OS will decide based on a number of factors, e.g. memory usage. I can only think that partially uncovering has a timer (IIRC) that may be keeping things active. Do you have a 30s file close timeout set in the preferences? How are you switching between apps? Do you press the home button and then the app icon, or do you use the task switcher? I usually have good luck with the task switcher and don't see odd closes.
Is the file in a special folder or anything in gdrive? Is it shared or anything? I just tried opening a file from gdrive, and it worked ok. Do you use a Yubikey or saved password with it?
passwdsafe: file: Set a minimum for password hash iterations when saving
passwdsafe: file: Update format minor version
passwdsafe: test: Fix tests for Yubico header field
test: Add test file with corrupt Yubico header
gradle: Update
passwdsafe: PasswdSafe 6.27.2