Hi Aeneas,
We are sorry, this is a bug. Collapse and Expand events don't work.
Here is a workaround.
Collapse: preApperyio("mobilecollapsblockName").on( "collapsiblecollapse", function( event, ui ) {
//your code here
} );/pre
Expand: preApperyio("mobilecollapsblockName").on( "collapsibleexpand", function( event, ui ) {
//your code here
} );/pre
Where mobilecollapsblockName is a name of collapsible block.