Orianna's Ball Prevents Lantern Clicking
The subject says it all, really: If 
Orianna moves her ball over 
Thresh's lantern, even though it's a non-targetable unit, it prevents anyone from clicking the lantern under it.
3 Comments
This is unfortunately a known issue that is surprisingly difficult to address. Similar champion related particles/abilities cause this problem as well such as Zed's shadows. It will also make it more difficult to target/last hit a minion.
In the near future we hope to have a list of all known issues and this one will definitely be included.
Sorry I couldn't be more helpful, but this type of bug would take a substantial system overhaul and provide comparatively (to other more serious bugs) less value.