Hi,
Currently the Experience Builder Map Layers widget - search function filters the layers that match the search text.
That results in some odd behaviour.
If the search string matches a group name, it will return the group, but when you expand the group, it looks as though the group is empty:

If the search string matches a layer name, it returns the group the layer is in, but doesn't expand the group so you can't see the layer:

until you expand it:

You can try this for yourself on our main public facing mapping website https://experience.arcgis.com/experience/a3074c31108a43ada55e21e660bc043d.
It's a great tool, but our users don't find it very intuitive. I would like an option to highlight the layers that match the search text instead, expanding the groups where necessary.
Thank you,
Sarah