This video shows the problem I am having when trying to drag elements on a calendar.
Here is how the workflow is configured.
I found the problem…on the workflow I was updating the current event and not the modified event. This was updating whichever event I had selected previously.
Hello @ianhayes2121,
Thank you for getting in touch.
After carefully checking the shared details and video you’ve provided with our dev team we find out that the plugin library does not support this option to resize the 2 calendar events simultaneously by dragging one of them above the other.
Only one event at a time.
Let us know if you have other plugin-related questions, we’ll be glad to cooperate. 
Thank you for understanding and have a great weekend ahead. 
Best regards