sortable widget leaves style="display:none;" on sortable item after drop when web inspector is open in Safari

sortable widget leaves style="display:none;" on sortable item after drop when web inspector is open in Safari

I'm using sortable widget (jQuery ui v1.12.0)
I have multiple lists of sortable items (DIVs) that are all connected so that an item can be moved between lists.
When I drag a DIV from one list to another, a "style=display:none;" modifier is left on my DIV after the DIV is dropped. Is this a bug in the sortable widget, or am I doing something wrong? How do I begin to debug this issue?

a little help?

thanks,
Mark