This is more of a tech question. 3 days ago, a program I use, that connects with an excel workbook and they interact, won't load anymore? In the 3rd party's screen it says it's connected but Task manager confirms that it isn't and the screen is blank of the workbook.

The software providers solution is to use system restore to an earlier period, but just yesterday Office 365 upgraded excel to 2016 (still won't work with the 3rd PS), so I see that as a backward step? They blame excel, but what would've happened to excel to prevent it opening to a request to open all of a sudden after nearly a year of working daily. Excel on it's own has no issues.

I'm kinda stuck as the 3PS people can't offer a plausible solution. I can't use it anymore, and it's how I make my living.