This occurs on time sheets and jobs grid on all tabs. I assume that it happens on any screen in the program.
When making a change on any screen or tab and then moving to another screen, or even a tab on the same screen, the changes are lost without warning. Many times the save button is not showing on the screen and the screen needs to be scrolled to even notice it is there. Most other web app that I use give a message that you have made changes and asks if you want to save the changes or leave the page.
Specific examples are entering detailed descriptions on time sheets. Adding jurisdictions on a job, Changing status on a job, etc.