I get a javascript error when I issue a load() while there are pending changes.
I can reproduce using this example:
https://bryntum.com/products/schedulerpro/examples/dependencies/
Add this button in the tbar:
{
type : 'button',
text : 'Refresh',
onAction : () => scheduler.project.load()
}
Open browser debugger console, drag and move any event, then click the refresh button.
It show this javascript error, and the scheduler is now unresponsive to drag&drop or resize event: