I think you should set your code to datasets, not data. I show the code below as an example. I am usually using this code while making loaders.
export function loadingStrip_viewportEnter ( event ){
$w ( “#loadingGif” ). show ();
$w(“#dataset”).onCurrentIndexChanged(function(){
$w ( “#loadingGif” ). hide ();
})
}
https://www.wix.com/velo/reference/wix-dataset/dataset/oncurrentindexchanged