The analysis belongs to the clip exactly as it was when you analyzed it. Visions keeps checking the picture against it, and when the two stop matching it switches the geometry off rather than draw it in the wrong place. Here is what each edit does.
Trimming a clip shorter keeps the tracking. Trimming the head in Final Cut, or moving a layer in Motion, keeps it too: the button reads Checking clip… until you play over the clip for a moment, then Tracking ready.
Making the clip longer
More than 1 second
The tracking covers the whole clip or nothing. Extend a clip by more than about a second at either end (in Motion, by more than one frame) and the button reads Clip changed (or No match yet on new frames added at the start), and the geometry draws nowhere until you analyze again. In Final Cut, a second or less is fine: the geometry holds the nearest analyzed frame and fades out over the new frames. That way it can never quietly stop halfway through an export.
Transitions added afterwards
Final Cut fades
A dissolve added after analyzing makes the clip reach into frames that were never analyzed. In Final Cut, up to a second of that is fine: the geometry holds the nearest analyzed frame and fades out with the dissolve. Transitions longer than 2 seconds read Clip changed; analyze again with the transition in place. Motion does not fade. If the last analyzed frame is black or nearly blank, extending past it reads Clip changed too.
Slowing a clip down reads Clip changed, or Different clip on moving footage; a small slow-down on a still shot may not be caught. Speeding it up keeps it inside the analyzed range, so Visions may not catch it, especially on a shot with a still background. After any speed change, analyze again. Undo the retime instead and the tracking comes back once you move the playhead.
Another frame rate
Analyze again
The analysis belongs to the frame rate of the project it was made in. Copy the clip into a project at another rate (24p into 30p, 29.97 into 59.94) and it reads Clip changed. Changing a clip's Rate Conform frame sampling afterwards changes the in-between pictures but not the rate, so Visions does not reliably notice: analyze again after changing it.
Pasting Visions onto another clip
Analyze the new one
The pasted analysis belongs to the old clip. A clip with different content usually reads No match yet or Different clip. Careful with another take of the same setup: the shots look alike, so the check can pass at first and catch the difference later, even mid-export. After pasting, always analyze again.
Changing the picture underneath
Titles · compounds · relinks
Visions re-checks the picture against the analysis every few seconds. Edit a clip under an analyzed Visions Title, edit inside an analyzed compound clip, or relink to other media, and the geometry switches off a few seconds into playback with Different clip. Undo the change (or relink back) and it returns once the playhead passes that spot again. If you keep the change, analyze again.
Exporting XML
Analyze again
File ▸ Export XML carries your Visions settings and the look's name, but not the analysis. After File ▸ Import ▸ XML, the button reads Analyze Clip: analyze the clip again, then check where the Periphery Center crosshair sits.
Motion: the filter's own bar
Motion only
In Motion, Visions analyzes its own filter bar, which is all the effect renders. With the bar starting where the layer starts, making the layer longer than the bar changes nothing, and trimming the end of the bar keeps the tracking. Extend the bar's end more than a frame past what was analyzed and it reads Clip changed. If the bar starts later than the layer, Visions analyzes the whole layer instead, so a long layer can read Clip too long even though the bar is short: trim the layer, or move the filter so it starts where the layer starts.
Very long clips
Split them
One analysis holds a set number of frames, and the picture's shape decides how many. It counts frames, not minutes, at the project's frame rate, so a 60 fps project gets there in half the time of a 30 fps one. Resolution doesn't matter: 1080p, 4K, and 8K of the same shape share a limit. The shape is the clip's own, so a 16:9 clip in a square project still gets the 16:9 limit. Shapes in between get a limit in between (16:10 holds 24,300). Over the limit, the button reads Clip too long as soon as the analysis starts: blade the clip into parts and analyze each one.
Anything that reshapes the picture
Set it up first
Visions analyzes the picture it is handed. Stabilization, rolling-shutter fixes, and the other effects stacked with Visions can all change that picture, so set them up the way you will deliver before you analyze, and analyze again after changing them. Same goes for other plugins still in their trial: their watermark gets analyzed too, so license them first.