trouble with calling onloadcomplete()

Hello to all,

I have a website that recently stopped working. The viewer krpano 1.20.9 (build 2020-11-19) is used there. Strictly speaking, the event onloadcomplete is no longer executed. Also no error message appears. The panorama is loaded correctly, but all other operations triggered by onloadcomplete are no longer executed.

So far I have used the following code:
Inside the HTML5

<script>var krpano<?= $this->contentId ?> = new MyKrpanoWrapperClass();  // this is resolved to krpano5896 etc to build an unique variableembedpano(  {    xml:    "{{env::url}}/<?= $this->panoUri ?>",    target: "pano_<?= $this->contentId ?>",    html5:  "auto",    mobilescale:1.0,    consolelog: !0,    passQueryParameters: true,    initvars: {      viewerDir: '<?= $this->viewerDir; ?>',      pluginsDir: '<?= $this->pluginsDir; ?>',      skinDir: '<?= $this->skinDir; ?>'},    onready: krpano_onready_callback});function krpano_onready_callback(_interface) {  krpano<?= $this->contentId ?>.interface = _interface;  krpano<?= $this->contentId ?>.setLookTo(<?= $this->hlookat ?>,<?= $this->vlookat ?>,<?= $this->fov ?>);}<script>

class MyKrpanoWrapperClass{    /********************************************     *     * @param panoramaId     * @param opt     */    constructor(panoramaId, opt = {}) {        this.ifc            = null;  // the krpano interface        this.target         = document.currentScript.parentElement; // the parent el of the embedded script        // more code ...    }    set interface(krpano_interface) {        this.ifc = krpano_interface;        // get path references        this.viewerDir = this.ifc.get('viewerDir');        this.pluginsDir = this.ifc.get('pluginsDir');        this.skinDir = this.ifc.get('skinDir');        // set callback immediately after initialization         this.ifc.set("events.onloadcomplete", this.onLoadComplete.bind(this));    }onLoadComplete() {    alert("ready");   } }

i have now reduced the context to the following krpano_onready_callback:

function krpano_onready_callback(_interface) { 
_interface.set("events.onloadcomplete", function() {	alert("onloadcomplete() was triggered");});
}

But in the code above onloadcomplete is never triggered.

But this works well!

_interface.set("events.onloadcomplete", alert("onloadcomplete() was triggered"));

Is anyone aware of side effects that can trigger this behavior?

thank you very much for your reply!
unfortunately everything remains unchanged. The callback onloadcomplete is no longer executed.

I am at a loss
EDIT:
I have found a cause: replacing " with ' brings the solution.

_interface.set('events[myevent].onloadcomplete', function() { console.log("onloadcomplete"); });
_interface.set('events[myevent].keep', true);