Excel functions

[LucFlynth]

When using the following functions (sort and unique) in Excel (2016) I suddenly see the following error =_xlfn._xlws.SORT(_xlfn.UNIQUE(C4:C585)).

When I was working in this excel file last week, both functions worked fine. Today I was importing text files and suddenly these functions were not visible anymore. Could someone provide help?

[#2]

@LucFlynth 

The functions you mention (SORT and UNIQUE) are only available using Microsoft 365 or Excel 2021.  The mystery is how the functions ever worked for you.