LR: Colored bar at bottom of picture after export

Hello,

I am desperatly looking for a solution for my following problem. I hope someone else here does have an idea how to solve that problem.

I am using Lightroom mobile for my RAW photo editing. After exporting my photos as a JPEG (settings: quality 100%, no extra sharpening, sRGB) on the bottom edge of the picture a bar of colored pixcels occur. In some pictures its more serious than in others. Before exporting, so in LR this colored bar does not exist in the photo.

I attached a cutout of the lower part of the photo to better illustrade what i mean.

I would be really happy if someone here has an idea how to fix the problem.

Daniel