P: (Android) is not importing images between LG and Samsung

I bought a new LG-mobilephone and did install Lightroom CC mobile. When I know get images (Picture(JPG)) per WhatsApp or SMS or Threema from a samsung-mobilephone I can save them in my own (intern) picture-menu. But if I try to import them to Lightroom cc mobile the system says "the import is not possible". In the other way from LG to Samsung it is the same.

If I send the picture I get from a Samsung-phone to an Apple-Iphone and then back to my LG-Smartphone I can import the image (JGP) to Lightroom cc mobile.

Is their a bug???