It is most likely a privacy rule issue. Not really an issue, but it might not be able to verify the value in time. Is this only when you are creating this item? Is the creation process being done on a backend workflow? What do your privacy rules look like?
I don’t think it’s a privacy rule issue. If that was the case then the rest of the Teams wouldn’t be loading either, but they are.
I found a solution. The data source was doing a search for Teams.
So what I did was simply add the correlation between the Teams and the current page’s League and change the data source to: “Current page’s League’s Teams”.