Danger/diagonal stripes on clips are typically the result of working with mixed frame rates between PluralEyes and Premiere.
To workaround this problem, setup your sequence in Premiere using a frame rate that matches the highest of the clips you're working with, then send your sequence to PluralEyes for syncing.
For example, if you are working with a 60fps clip and a 24fps clip, you'd want to setup a 60fps sequence. Right-click your 60fps clip in your Project panel and select New Sequence from Clip
Once the sync is complete you can set your Premiere sequence back to whatever frame rate you like.