The Upwork desktop app has a time-caching mode so you can continue logging time through minor Internet connection issues or Upwork site maintenance. Usually, the cache will automatically upload as soon as your connection is reestablished so the time can be included in your weekly invoices. The latest version of the desktop app can cache about 12 hours at a time. Once it is full, you can no longer log time on any contract until the cache is uploaded. The most common causes of time-caching mode are:
Upwork maintenance – Upwork undergoes periodic, and usually brief, downtime for maintenance. During this time, you can continue to work and your logged time will be held in the cache. It should reconnect and upload the cache within an hour
Unstable Internet connection – The desktop app, especially when trying to upload logged time, requires a stable Internet connection. It should reconnect and upload the cache automatically as soon as the connection stabilizes, usually within a few minutes