Keyframes stop working
Try this: If you have Ripple Callouts, put in the Line Solid. Now, keyframe one end of that line. Play a few seconds, and try to reposition the position of that same end of the line. You're setting a new keyframe but you can't see what you're setting because the end of the line is not moving with your adjustment. This is no fault of the Ripple effect. The same thing happens on my own homemade line. The same thing happens on both of the computers I work on as well.
I'm an experienced user. Suddenly, changing a position keyframe of an effect visually stops after the first keyframe is set but the new position is set. I just don't see the graphic move as I adjust. This is happening on my 2013 Mac Pro at work using High Sierra and on my home 2013 Mac Pro with Mojave. I'll add a simple double-headed arrow from a vendor, (however, the same thing happens with a homemade double-headed arrow I made in Motion), and attempt to set keyframes on one end to track a moving object. Try the Line Solid from Ripple Callouts (remember, it's not the callout. This happens on my own similar effect) Fine on the first keyframe, but when I try to set the second keyframe, the control for repositioning the head of the arrow becomes visually unresponsive. I can see the keyframe is set, but the arrow head I'm trying to reposition is not displaying any movement as I adjust the keyframe. I'm repositioning in the blind! If I play through the keyframe, the animation happens but without seeing the position as I adjust the keyframe, the animation is just wild. I had also already 'anchored' the other end of the arrow with a keyframe but I can un-anchor the other end and it still does not solve the problem. I know more than anyone I know about Final Cut Pro X and I'm just stumped on this. To be clear, I can change the overall position of an object without a problem. It seems to be callouts where you can adjust, say, one end of a double-headed arrow. Interestingly, I can add an effect I once created following a Ripple tutorial where I connected joints of a line by tracking the joints and pairing each joint with a shape. It's a 7-point box. Each joint moves visually just fine. That tutorial is kinda old and I'm trying to find it to create a simple double-headed arrow where each end will move as I put multiple keyframes on it.
UPDATE: Found the tutorial...
... And I created it. Works fine on its own but hangs like the other effects once a keyframe is set on the other end. In short, they keyframe is being set invisibly. It's just the onscreen object doesn't follow so you can see where to set it.
There has been a bug for a long time where certain outline/strokes on motion shapes didn’t update until you clicked in the timeline. But they were rare and were fixed in most recent version. But perhaps they just moved the bug to your issue.
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Clock Maker http://bretfx.com/product/bretfx-clock-maker/
Thank you, Bret. I worked around the problem by brining the video clip into Motion and keyframing each end of a double-headed arrow so that each arrow following a moving target. Incredible that something like that won't work on the FCPX timeline.