Say you have 2 lists which are connected to a filter.
You search something in the filter, then drag-and-drop things from one list into the other.
If the target list was originally empty When the filter is un-applied to the items, they will be visually removed from the list.
Here is a snippet that can be used to reproduce the issue: https://snippet.dhtmlx.com/svq3dhu1
And here are screenshots of each step:
