We have been experiencing problems with using more than two filters on a dataset lately, so this would probably be the first place start. Rather use query instead of filter as per this article, it is a bit more robust:
It should look something like this:
wixData.query("yourDatabaseNameHere")
.contains("instruments", $w('#sInstrument').value) .contains("classification", $w('#dropdown1').value)
.contains("city", $w('#dropdown2').value)
.contains("state", $w('#dropdown3').value)
.contains("school", $w('#dropdown4').value)
.find()
.then( (results) => {
$w('#table1').rows = results.items;
})
$w('#table1').show();
} )
Let me know if this solves it!
Tiaan