Hummingbird doesn't seem to think images are smushed, when they are.

Hi,
I'm not sure if this is an issue with Hummingbird or with Smush but on one of my domains, barwellwindows.co.uk Hummingbird gives me this report:

Benchmarks

Optimize the following images to reduce their size by 2.2MiB (68% reduction).

Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/09/bi-fold-door-03.jpg could save 951.8KiB (67% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/09/bi-fold-door-01.jpg could save 722.8KiB (71% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/09/bi-fold-door-03-1024x768.jpg could save 296.3KiB (68% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/09/bi-fold-door-01-1024x639.jpg could save 227.4KiB (70% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/10/Liniar-163x70-4601.jpg could save 1.6KiB (32% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/10/Liniar-Energy-Plus-89x70-1986.jpg could save 1.5KiB (36% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/10/Liniar-Modlok-91x70-5804.jpg could save 1.4KiB (36% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2017/03/gqa-qualifications-mtc-compliant-86x70-9968.jpg could save 1.1KiB (27% reduction).
Compressing http://barwellwindows.co.uk/wp-content/themes/upfront/img/blank.gif could save 1KiB (93% reduction).
Compressing http://barwellwindows.co.uk/wp-content/uploads/2016/10/QA-National-Warranties-78x70-8726.jpg could save 823B (23% reduction).

But when I go into the media library, Smush tells me that all images are smushed!
Please can you tell me where the problem is & what the problem is?