You had already done most of the standard troubleshooting I’d usually recommend when running into a similar issue. Since the Fab plugin browser utilizes the WebBrowser component in engine, the data for that module isn’t expressly shown in the engine output log (though not sure how much it logs yet since it’s a web container) so I’ll have to do a bit of digging to see how to get those.
I’m going to try and compile more information on this and see if I can submit an updated report.