How do you take a light trail photo without the dotted line in the picture below?

Bruhnswik, this is weird, does the dotted line appear in every long exposure picture? Any chance to provide us the original footage for further analysis? You can upload it to Dropbox or Google Driver if possible, thank you.

DJI Mindy Posted at 2018-1-5 02:19
Bruhnswik, this is weird, does the dotted line appear in every long exposure picture? Any chance to provide us the original footage for further analysis? You can upload it to Dropbox or Google Driver if possible, thank you.

I just used the light trail feature, and that is the original picture I have.

bruhnswik07 Posted at 2018-1-5 08:27
I just used the light trail feature, and that is the original picture I have.

It seems not since the size is only 82.73KB.
May I know what mobile device you are using? Android or iOS? Thank you.