To double check for typos. Maybe I typed 189/12 instead of 188, maybe I type 180/12. Sometimes it's more like +3+4/12+3/16/12. I just want to make sure I typed the right thing, and it's near impossible when I only see the result and not what I typed.
It seems to happen only since I upgraded to Office 2016 (I had 2010 prior to that) and only in formatted cells.
If it is a new "feature" of Excel 2016, I cannot test it. I might suggest that you provide some of the details of your spreadsheet, so that one of us can recreate the spreadsheet as accurately as possible. if you can upload a sample sheet (with formatting and such all applied), that would probably be the easiest way to show the different variations in entry and formatting details that you are encountering.