Passwords in Keychain Keep Getting Deleted

Ever since I installed Catalina most of the passwords in one of my keychains keep getting deleted (all but about 10 passwords are removed from the keychain which originally contained about 100). All of my other keychains seem to be unaffected. Luckily I was able to restore the keychain from a back up, but its contents keep getting deleted on almost a daily basis, leaving the same set of 10 or so passwords. So each time I need to actually look at a password, I need to restore from backup which is incredibly annoying.

Today I finally figured out that it seems to be caused by an external app's request to use the keychain, when I noticed a popup window stating that the reminders app wanted to use the keychain. The popup prompted me for the password to the keychain and would not let me cancel the prompt without entering the password. I ended up opening the keychain app, saw that the particular keychain was in fact locked, so I entered the password in the prompt, at which point I saw the passwords in the keychain being deleted, leaving the same set as described above.

How do I prevent other apps from requesting access to and subsequently deleting the large majority of passwords that I have stored in my keychain? Also, why would an app such as reminders be deleting, let alone even need access to any of the passwords in my keychains? This was never a problem before I installed Catalina.

Thanks!