Not exporting compressed images when using Sketch 50.2

[sampeniak]

Following the two different ways in the docs, results in nothing happening, i.e. the images don't get compressed. This happens in Sketch 50.2 and has been tested on two different Macs.

[MrBran4]

Same thing is happening to me on 54.1 - when I go to Plugins > Sketch Image Compressor > Export All Assets it asks where to put them, then hangs for a bit (presumably while Sketch is generating the images?), and then doesn't put any images in the output folder.

My artboard names have slashes in them, which usually causes Sketch to generate subdirectories in the output folder. Does Sketch Image Compressor support that?