GUI "Update Manager" incorrectly show "Your System is up to date" at startup

[glenndk]

Describe the bug
GUI "Update Manager" 6.0.9 (mintupdate) incorrectly show "Your System is up to date" at startup by default.

When I a few seconds later press "Refresh" many updates are downloaded, and can be installed. I have discovered this behaviour at least three times.

To Reproduce
Steps to reproduce the behavior:

1. Open GUI "Update Manager"

Incorrectly show "Your System is up to date" at startup by default.

Expected behavior
GUI "Update Manager" should automatically make a refresh so it can detect if packages needs to be updated - but not download packages (can take a long time) - and then present a correct message; e.g. "no network access", "There are updates - press refresh" or "Your System is up to date"...

When GUI "Update Manager" has made an update, it should automatically make a refresh right after, to check if there is more packages that needs to be updated.

When GUI "Update Manager" is open, then it should automatically make a repeated refresh so it can detect if packages needs to be updated every 1 hour?/1 day?

Distribution:

• Linux Mint
• LMDE
• Other (please specify)

Software version:
GUI "Update Manager" 6.0.9

Locale:
"en US.UTF-8"