Thanks for the screenshots. Hard to deny something is wrong here.
Unfortunately I am unable to reproduce the problem.
Can you tell when the hours starts displaying wrongly? Is it right after you create a work unit manually or after you stop the timer. Or every time after you restart the app?
Also, when this problem happens, is it being resolved by either navigating to another screen (e.g. settings) and back? Or scrolling the list further down and back up again?
If there is a situation where the total is wrong even after restarting the app, it would be great if you could send me a backup of your database for me to better investigate this (and to determine if the problem is a display problem or if there are actually wrong times store in the database).