New features you were using in Office applications seem to be no longer available. These missing features could be IFS, MAXIFS, and MINIFS functions in Excel 2016, ink effects in Excel, Word or PowerPoint 2016, or any of the other new features listed in What's new in Microsoft 365.
This can happen if you had a Microsoft 365 subscription on your PC and then switched to a one-time purchase of Office 2016.
For example, you may have purchased a new PC that had a 1-month free trial of Microsoft 365 and, when the trial expired, you installed a one-time purchase of Office instead of activating the trial. Or, you may have payed for a monthly or yearly Microsoft 365 subscription but then decided to switch to a one-time purchase of Office instead of continuing with the subscription.
Microsoft 365 (including the Microsoft 365 trial) has exclusive new features while one-time purchases of Office 2016 receive security and performance updates but no new features.
We apologize for any inconvenience this may cause and we're working on making this experience better to explain clearly why the new features are not available.