I cannot insert a tiff file into a draw document. Error message is that the image format is unknown. This is true both when dragging the file into the program window, or using the menu insert → image → from file. The open dialog appearing in the second variant explicitly lists tiff files in the file type select drop-down element, so tiff should be supported. The tiff file was generated using ImageMagick, Windows is showing a thumbnail and the image opens fine in a viewer like irfan view.

It took me a while to find out that the reason was that the tiff file had been produced with 16 bits colour depth per channel. Converting the image with gimp fixed the problem.

Solution should be to change the error message appearing to something meaningful, like: “Tiff images with 16 bit colour depth are not supported.”