alt-enter (cell line breaks) is not working in Excel 2016

This problem (Alt+Enter not working) has driven me crazy for nearly a year now.  On multiple computers too! It just would not work.  It used to work.

Well i solved it tonight in a mad frustration. 

All i did to make it finally work was to

press  {Windows Key}+{Alt}+{Enter}

and it worked!!!!!

No idea why we need to press the Windows key - but IT DOES WORK

Hope this helps everyone!!!

Alright.  I'm not sure what is going on, but I have gotten the command to work intermittently.  I have found if I alternate between the left and right <Alt> keys I can get it to work in either program.  At least I know I can get it to do what I want, but it is still a mystery as to why I have to try so hard.  The <Alt> key works every time I press it and the <Enter> key works every time a press it.  But when pressed together, well, refer to what I typed above. 

Thank you for your help.  If you find a reason this happens, please let me know.