I'm running QGIS3.4.4 on a mac (OS:10.14.2). The Processing Tools don't appear to work.
I'm working through the examples in 'Learn QGIS -4th edition' from Packt> which uses the official qgis_sample_data for Alaska. So I assume the data and loading are clean. I've used Processing Tools successfully in earlier QGIS versions (currently 2.14), but can't get them working for 3.4.
The lastest failure is on 'Clip Raster by Mask Layer', reports similar problems to earlier failures - saying, 'layers not correctly generated'.