Is FCPX object tracking completely broken?

I'm relatively new to FCPX, but know my way around other pro software such as the full Adobe Suite, Premiere Pro, Davinci Resolve etc. I'm using the trial version of FCPX for now and so far have been getting around pretty well. I'm currently editing a 4K video which will turn out approximately 75 minutes long, with a bunch of screenshots and motion graphics, which is mostly just highlighting parts of the text in the various screenshots as they animate.

From the outset, I found the object tracking is really having trouble. The tracker itself seems to work correctly, once the "Analyze" process is complete. If I skim the clip, the tracker wireframe is rock solid, tracking and following the target perfectly. The problem is trying to attach something to the tracker like a basic generator shape or text - it simply will not follow the tracker. The shape/text object shows as assigned to the specific tracker, but during playback, the object stays put and will not move with the actual tracker.

I've tried this on multiple clips and screenshots with very random results. Through incessant clicking and adding, deleting then re-adding objects (and clips) then manually re-analysing the tracking, I have managed to get one or two objects to track, but mostly I can't get them to work at all. I have no idea why sometimes it worked and other times it just won't play ball with all the settings the same.

I have restarted FCPX and also my iMac several times. It doesn't seem to make any difference.

Is there a cache or similar that needs to be cleared? Or, is this just one giant bug and i'm wasting my time trying to use a feature that really doesn't work anyway? Any help or assistance would be much appreciated.