Designer beta 1.9.0.834, Windows 10
I insert a jpeg picture and sweep across it with the transparency tool (linear). Nothing happens.
If I do the same in Publisher beta or Designer 1.8.5.703, I get a transparency gradient.
If, after sweeping the jpeg image with the transparency tool, I rasterise it, the gradient appears but the 'Type' field in the context toolbar is greyed out.