Bryntum Support Forums

In order to reproduce the bug you can start from this demo https://www.bryntum.com/examples/scheduler/eventmenu/
adding the following listener

listeners : {
        beforeeventdropfinalize(event) {
            console.log(event.context);
            console.log(event.context.valid);
            event.context.async = true;
            setTimeout(() => {
                event.context.finalize(true);
            }, 100);
        }
    }

If you drag an event keeping the same timing and without going into another resource area the event won't go back to it's previous position.
The problem is also visible in a multi row condition, when you try to rearrange events, and steps are the same.
We tried logging the context and we have seen that the problem arises when timeDiff is 0 and hence valid is false.
Here attached you can find 2 pictures of the ending condition.

It looks like a bug. Thank you for reporting; the issue is here: https://github.com/bryntum/support/issues/2239