Wow, finally found this thread and noticed that it happened not only to me as I had encountered it for since last month also.

Same android phone, same image.

Cannot post image, from phone while outside my home, using own mobile data.
But,
Can post SAME image, from SAME phone while inside my house using WIFI connected to my Time Internet line.

Text messages something about, ..
Cloudfare, .....need to confirm human ...... After click, ...just direct back to lyn homepage.