decktalk check reports it when it judges the project’s files before a build, decktalk record when it records the pages, and decktalk verify when it measures the finished film and reads back each recording log.
Pass --allow PAGE_MOTION_UNDECLARED to carry on past it, and --fail-on to choose which severity fails a run.
What to do
Declare it as a motion withdata-motion or DeckTalk.motion, or as a loop with data-loop, or give its frame hook the region it draws in.
Troubleshooting says more under A motion verify cannot measure.