ebay://, tel: etc not working out of browser

I'm using Opera as browser. I can remember that in the past, when I googled a restaurant, I could dial the phone number right from the search results. Now, I see in the title bar tel:, but the dialer doesn't open. In addition, I just noticed that an ebay:// link does also not open the Ebay app but does nothing. Any idea what I have configured for achieving this behavior? And even more interesting: how can I restore the original behavior?