I've been playing around with some experiments with Datadrops and I'm noticing that I am not able to submit images to a Databin from neither my raspberry pi, Mathematica Desktop 11.0 or from Wolfram Cloud. All three of them return the same error messages:

StringJoin:String expected at position  2  in 
https://www.wolframcloud.com/objects/<>First[$Failed][UUID] 

CloudObject:No CloudObject found at the given address

It does create an object in the DataDrop with some size (a couple hundred kilobytes) but the data is unusable and just displays $Failed.

This is the test code I'm using:

bin = CreateDatabin["Interpretation" -> {"img" -> "Image"}]

timage = ExampleData[{"TestImage", "Elaine"}] 

DatabinAdd[bin, <|"img" -> timage|>]

I've tried a few variations like creating the Databin without a contract and simply doing DatabinAdd[bin, SomeImage] - all resulting in the same error.