Part of the reason noone ever noticed it before is because it's a good 30 degrees off the ecliptic. Tyche, for lack of a more appropriate name (see Tyche Hypothesis, it's close enough for now), isn't in the typical places we've been searching. There's clearly a presence of an object, BUT it's not like the case of seeing 17 stars in tight orbit around a black hole. The objects in question are in a clear arc, but not immediately under strong gravitational effect.
It's akin to looking at a parking lot with some cones on it, seeing a few of them sideways and flattened - you can tell that a car knocked them, and can tell what direction and how fast the car was going and where it was, but it's a big parking lot - and that won't tell you where the car is at the moment.
Fortunately for the sky survey guys, searching outside the ecliptic will be a lot easier. you won't get a lot of false-positives from unspotted Oort objects; whatever's moving out there is going to pretty much be by itself against the background stars. At ten times earth's mass, even a rocky body will be over twice the size of earth itself (say, 16-17,000 miles across) and have a very easy to spot signature. If it's a small gas giant, then it'll be a lot bigger than that, and might just be a fascinating 'ice cream scoop' of the Oort cloud itself. Either way, an IR search should find it soon enough...
...but I'll bet you every planetary astronomer is gonna blow their spare time hunting this one. Talk about the chance to stand among giants with spotting the first new planet since 1930.