@Antonio_Marino Ok I see we have an issue there.
We are currently working on a fix, but I can’t give you any ETA for now. But, I can provide you a workaround to make things working back. Just follow these steps:
1 - Set the Partner collection as not visible using the layout editor
2 - Reach the Partner collection settings, and observe that the option is now clickable.
3 - Activate the option
4 - Save your changes
5 - Set back the Partner collection as visible
6 - Then you should be able to search using your widget as you are used to.
I hope this helped out, please keep me in touch 
Steve.