No flavor found in the Distribution Wizard

Situation: 

I wanted to install the "XWiki Standard Flavor" for 15.0

The issue is, that if you type in the search line there´s no search result. 

You have to push the button "Install this flavor", afterwards return to the search line and if you type in the search line there will appear the installable flavors (see attachment). 

1. Type in search line
2. No result
3. Push "Install this flavor" 
4. Type in search line again. Flavors appear
5. Choose flavor and click "Install