Read the Mac's sync status
The meaning of each status line in the macOS menu bar, which failed uploads the Mac retries on its own, the line for a day waiting for your review, and the Sync now button.
Where the status line is
Open the companion from the menu bar. The line under Achetrace at the top of the panel is its status. The lines below are the ones a paired Mac shows. Needs pairing means the Mac is not paired, or no longer is: see Pair the desktop companion, or Reconnect a Mac whose access was revoked.
When an upload problem and a pause apply at the same time, the status line shows the upload problem.
Tracking active
The Mac is paired and recording desk time, and no upload problem is showing. After an upload, Last synced and a relative time show when it last uploaded.
Paused
You chose Pause tracking. The Mac records no desk time until you choose Resume tracking, and stays paused if you quit and reopen the companion. Days it recorded before the pause still upload.
Offline - retrying
At least one day of desk time failed to upload and is waiting to be tried again. Usually the Mac failed to reach Achetrace, or Achetrace had a problem of its own. The waiting days stay on the Mac and are retried automatically, and the Today card shows the number waiting to sync.
Upload error
Something on the Mac went wrong, and a message in the panel names it. Two messages lead here.
"Desktop activity sample was invalid." means a stretch of activity the Mac measured had an end time no later than its start time, so it was not recorded. The Mac keeps going, and the status line is replaced at its next upload attempt, within five minutes.
"This Mac isn't fully connected yet. Pair it again to start syncing." means the Mac is paired but is missing the details it needs to upload. It is not retried. Choose Disconnect this Mac, then pair it with a new code from the web app. Disconnecting removes anything still waiting to sync from the Mac.
A revoked Mac does not show Upload error; it shows Needs pairing.
Tracking unavailable
The companion defines the Tracking unavailable line, but no current version of it sets it, so you should not see it.
Sent. Waiting for your review
"Sent. Waiting for your review in Achetrace." appears on the Today card, under Last synced, when the Mac has uploaded today's desk time and Achetrace is holding that day until you review it instead of using it straight away. It is not an upload problem, and the status line does not change.
The Mac keeps uploading today's desk time as the day goes on, and nothing stays waiting on the Mac because of it. The line is about today only: a day before today that is waiting for your review shows no line on the Mac. The line goes away when a later upload finds the day is no longer waiting, when the date changes, and when the Mac is disconnected or its access is revoked.
Which failures are retried
While the companion is running and paired, it checks for desk time to upload every five minutes.
Retried automatically: a day whose upload failed because Achetrace was unreachable from the Mac, or had a temporary problem of its own. The Mac waits 2 minutes before trying that day again, then 4, 8 and 16 minutes, then 32 minutes between every later try, and keeps trying for as long as it is paired and running. Because it checks every five minutes, a try can come up to five minutes after its wait ends. Waiting days are kept if you quit the companion, and are tried again after you reopen it.
Not retried: a day Achetrace refuses as invalid. That day is removed from the Mac and not sent again. If you are still at the Mac on that day, a later upload sends the whole day afresh; a day that has already ended is not sent again. The status line can go back to Tracking active afterwards, and the panel may show no message about it.
Not retried: an upload refused because the Mac's access was revoked. The Mac stops uploading and shows Needs pairing until it is paired again.
Sync now
Sync now uploads straight away instead of waiting for the next five-minute check, and tries every waiting day even if that day's wait before its next try has not ended. It is in the panel only while the Mac is paired, and cannot be chosen while an upload is already running.