I am trying to use INDEX MATCH with 2 matches across two different sheets however multivariable matching only works on Excel Desktop and not Excel Online. I need this to work on the online version because of the auto-sync with a Microsoft form. I made a simpler example for the purposes of this question. I tried different ways of referencing sheets in the formula but I believe the syntax in the picture is correct.
Sheet1!A2 should match with rows Sheet2!A1 and Sheet2!A4;
Sheet1!B2 should match with rows Sheet2!B2 and Sheet!B4;
The MATCH formula should output 4