Autodesk events not being triggered on iPad

We have an issue with Autodesk viewer when on Safari on iPad. We have event listeners in Javascript attached to Autodesk.Viewing events (specifically Autodesk.Viewing.OBJECT_TREE_CREATED_EVENT), which are fired on desktop, but not iPad.

The event listeners are added in JS (and the code to add is being run) as follows:

viewer.addEventListener(
    Autodesk.Viewing.OBJECT_TREE_CREATED_EVENT,
    handlerToCall
);

I have tested by connecting an iPad (9th gen, iPadOS 18.0.1), attached to Web Inspector on Macbook. I added Event breakpoints for the Autodesk.Viewing.X events, but they are never hit (other non-Autodesk breakpoints are hit e.g. DOMContentLoaded), so that rules out general events not being hit.

I know that there are other ways of reacting to events – but would prefer not to have to use a different method if possible (e.g. aps.autodesk.com/blog/wait-events-viewer)