I was making a motion study, and some yellow lines appeared out of no where and messed up the study.

The yellow lines is at the 18-19 second position. They didn't appear until I almost finished the whole study. At the end, I clicked the "Play" button and the study started to run from the beginning to the end. Out of nowhere, the yellow lines showed up and made the study a little messy. I have no clue where they came from and how to fix it.

Any help is appreciated.