First, use ChromePass to see how many of Opera's passwords it picks up. How many does it show?
The downloaad link for the zip file is down the page a bit. There's also a password listed below the download link that you'll need to extract the zip file. Also, before you download the zip file, in Settings in Windows, goto "Privacy and Security" -> "Windows Security" -> Virus and Threat Protection" and click "Manage" under "Virus and Threat Protection Settings" and disable "Real-time Protection" until you're done using ChromePass.
At the URL opera://password-manager/settings, you can export your passwords to a CSV file and open the CSV file in a text editor to see if you only get 4 entries or all 30.
Also see https://forums.opera.com/post/398128 to see what my Python script is able to grab from your "Login Data" file.
All of that should tell you if it's just Opera that's messed up or if it's your "Login Data" file itself. If the latter, you're out of luck and you'll have to save what passwors are there, delete the "Login Data" file so Opera creates a new one and then manually type in your username and password for sites and save them.
If you've recently changed your Windows account password or switch to or from Windows Hello login, the Login Data file might have gotten messed up.
Or, there might be nothing wrong with the Login Data file and Opera Sync wiped out most of them if you're using Opera Sync and syncing passwords.
