I've attached video for clarification.

To reproduce:

• Create QVariantMap or other container variable
• Fill it with some items.
• Set breakpoint after it is populated.
• Run debugger, and then in "Locals and Expressions" view try to expand items of that container, one after another.

When expanding second item (after first was expanded earlier), first item's subitem dissapears and so cannot be expanded again. If expanding third - second's dissapears.