SharePoint Framework - Extensions Deployment

Hi,

I've been looking at the spfx extensions samples. I deployed one along with some sample web parts to a site, specifically to an Site App Catalog. A strange thing occurred, there were 3 web parts that were working fine and you could see them in the site contents, however, when I deployed the extension (added it to the site app catalog then added the app in from site contents), the name/title of the extension replaced the names of the 3 web parts!

So, my question is, are extensions supported in a Site App Catalog.

VesaJuvonen

many thanks