Steps to reproduce the issue

Create a login module titled My Login Module
Create a banner to open in modal with the following in the Description field:-
{loadmodule login, My Login Module}

Expected result

Banner opens modal on click
Expect to see contents of the My Login Module inside the modal

Actual result

Source code of {load module...} is displayed.

System information (as much as possible)

Joomla 3.5.1
OSX Xampp

Additional comments

Tested the same {loadmodule....} in an article description and it works, so my {loadmodule} code is correct.