I know you probably posted it elsewhere but what is the Mac Address for this timer again?
I have seen this when the timer’s date/time get off. This can happen when the batteries are changed, it doesn’t have a way to store the date/time so it is reset to 1/1/2017 I think or something like that. They way to update the date/time after changing or even just pulling the batteries out is to launch the app and connect with the timer on a mobile phone via Bluetooth, the first thing the App does is ask the timer for its date/time and if it’s off the App will set it. The other way is if you have a B-hyve hub and it is connected to the internet, as soon as the timer reconnects with the hub the date/time on the timer should be update from the server.
(This is a long shot)
If you haven’t changed the batteries in a long time it could be that the timer’s date/time is drifting and is just off by that much, which should only be an issue for Bluetooth only timers since timers connected to a hub should be updated regularly.
Try connecting to it with the phone and let’s see if that helps. You will also get the correct battery percentage this way and will tell you what it’s currently at.