A tool shows no usage after I connect it
Open Settings → Accounts and check the tool is toggled on. Tools that read a local folder need that folder picked once in the system open panel; if you moved or renamed it, pick it again. Tools that sign in may need a fresh login after a password change.
The menu bar item disappeared
macOS hides menu bar items when the bar runs out of room, usually on a notched display with many icons. Quit some menu bar apps, or open Settings → Appearance and switch the display mode to the compact badge.
I bought Pro but the features are still locked
Open Settings → Pro and choose Restore Purchases. Make sure you are signed in to the same Apple Account that made the purchase.
Alerts never arrive
Alerts are local notifications. Check System Settings → Notifications → Fetchy is allowed, then confirm the threshold is enabled in Settings → Alerts.