If i do a request to your server to get information about the image that i will download, your server don't send me content-lenghth in header. The value is always -1.
Do you see a way to fix this on your new(?) image server?
That is the information i've found about this issue:
Expected behavior - property returns content length as set by the server, so if that header is not set you get -1 (which is likely behavior for large files that are streamed from server).
The ContentLength property contains the value of the Content-Length header returned with the response. If the Content-Length header is not set in the response, ContentLength is set to the value -1
