NavigationPanelAdministrationIT#navigationPanelAdministration is flickering

I checked the screen recording for this stacktrace:

org.opentest4j.AssertionFailedError: expected: <[Alice, Bob, Denis, XWiki]> but was: <[No pages found]>	
	at org.xwiki.panels.test.ui.docker.NavigationPanelAdministrationIT.navigationPanelAdministration(NavigationPanelAdministrationIT.java:125)

and I saw that:

• the Navigation Panel configuration section is saved and reloaded with an empty tree (No pages found)
• the test drags and drops pages from the exclusion list back to the tree
  • the drop area is highlighted (blue dashed line), so the tree is responsive, signaling that it can accept the dragged page
  • the page is dropped, but it's not added to the tree
  • the page is removed from the exclusion list though
  • the "No pages found" fake tree node is highlighted (gray background), so the page was dropped on top of it as expected

I can't reproduce locally so it's hard to debug further...