Off-canvas transition

Hi,

I have created an off-canvas panel which worked fine. It contains the output of a widget, showing last seen content by the visitor.

Lately, I am seeing a strange change in its closing behavior which I would like to fix.

The issue is, that when I close the panel it kind of stops half-way through and only then continues to fully close.

I use the following custom css in the customizer (I believe it is from your documentation):

/** Off canvas panel width - Start */
body .offside--left.is-open, .offside-js--is-left .offside-sliding-element {
    -webkit-transform: translate3d(600px,0,0);
    -moz-transform: translate3d(600px,0,0);
    -ms-transform: translate3d(600px,0,0);
    -o-transform: translate3d(600px,0,0);
    transform: translate3d(600px,0,0);
}
body .offside--right.is-open, .offside-js--is-right .offside-sliding-element {
    -webkit-transform: translate3d(-600px,0,0);
    -moz-transform: translate3d(-600px,0,0);
    -ms-transform: translate3d(-600px,0,0);
    -o-transform: translate3d(-600px,0,0);
    transform: translate3d(-600px,0,0);
}

body .main-navigation.offside {
    width: 600px;
}
/** body .offside--left {
    left: -600px;
}  These couple of lines used to work but now I have comment it out, because if they are active the content of the off-canvas panel is going somewhere 50% left and not entirely visible*/

body .offside--right {
    right: -600px;
}
body.offside-js--is-left.slide-opened .slideout-overlay button.slideout-exit {
    left: 595px;
}
/** Off canvas panel width - End */

Thank you!