Your images may be 32-bit and not 24-bit. It seems the only ones I've had trouble uploading are the ones that are 32-bit. You can see the bit amount of the photo usually in its details found in "file info" ( a little "i" in a circle icon). As for taking only 24-bit photos, to ensure success every time, it might depend on changing the camera settings for your device. A quick research of your device camera specifications online or how to edit the bit amount should do the trick. I hope this helped someone because it's the only thing that worked for me, but I am a bit late to the conversation.
