Photoshop CC 2015 - New layers are all white, not transparent

I'm running Photoshop CC 2015 on Mac OS X 10.11.

Since upgrading to Photoshop CC 2015 (2015.1.2 20160113.r.355) when I create a new layer it's all white, when I select pixels and press the Delete key the pixels remain white - I'm unable to get transparent pixels. The layer is a "normal" layer, not a Background layer.

I note this happens even when File > New > Background Contents: is explicitly set to Transparent.

Under Preferences > Transparency I have the default settings of Medium Grid Size and Light Grid Colors.

How do I get transparent pixels back?

UPDATE: I'm having the same issue as described here: https://feedback.photoshop.com/photoshop_family/topics/photoshop-cc-2015-checkerboard-preview-for-transparency-in-thumbnails-and-artboards-are-gone