Hi Jeff,
It’s no bug, but the server does additional compensation over the measured data. Here, the internal heating of the electronics produces a drift. Therefore, the correct info is displayed on the server. The best way to get the data is via the server API, presented ni the Dashboard.
In later firmware versions, the local data is set to match the server data. Would you like to update your unit’s firmware? It’s easy, see: https://www.uradmonitor.com/uradmonitor-model-a3-firmware-upgrade/