Missing placeholder for the first load of a LD table

When loading the Wiki manager for the first time after a subwiki is created, there's nothing that shows that a live data is being loading, so only the create button is displaying which is a bit disturbing especially since the LD takes a few time to load.
In my case I thought for a moment that I was on a wrong instance because I couldn't see any placeholder so I thought there was no subwikis at all.

We should always have a placeholder immediately visible when a LD is available, even if it's not loaded at all.