Yes — if your connection drops, WorkMonitor keeps recording locally and catches the server up automatically the moment you’re back online.
What this means for you
The tray icon’s tooltip tells you honestly what’s happening: it reads “Offline — buffering” while there’s no connection.
Your activity data — what you worked on and when — keeps being recorded on your machine and is held in a queue. As soon as the connection comes back, it’s sent in the background, oldest first, with nothing lost and nothing double-counted.
Screenshots are the one exception: they aren’t held for later. If a screenshot would have been taken during an outage, it simply isn’t — the rest of your activity for that stretch is still captured and synced normally.
The queue isn’t unlimited. If a machine were offline for an unusually long stretch, the oldest buffered data would be trimmed to make room for the most recent — an ordinary dropped connection or a commute isn’t something you need to plan around.
There’s nothing for you to do — WorkMonitor recovers on its own once the network problem clears, and you don’t need to quit or restart it.
Related
The menu-bar icon and pausing
Which operating systems does WorkMonitor support?