Is anyone else having quality issues with exports (jpeg and tiff) from Lightroom CC?

I've had every LR edition previous to LR CC and never experienced this until now.

My jpegs and tiffs are coming out very soft and with a really poor quality compared to when I view them in LR.

Here's what I see in LR:

and here's what I get on export:

It's hard to tell from those images but the images seem to be suffering from some kind of compression or degradation on export. I get exactly the same with both jpegs and tiffs. I've tried a number of things that didn't help at all. These include:

• Toggling off output sharpening in export dialogue.
• Changing jpeg quality from 80 through to 100.
• Adding/removing small text watermark.
• Ensuring no compression with tiff files.

Here are my jpeg settings that I've been attempting to use:

• quality 80
• sRGB color space
• resize to fit long edge, 1000px
• resolution 300ppi
• no output sharpening (I do all this in the develop module or via Nik Output sharpener)
• small text watermark (my website)

I'm using:

15" Retina MacBook Pro (late 2013),

2.3 GHz processor Intel Core i7,

16GB 1600 MHz DDR3,

NVIDIA GeForce GT 750M 2048MB

When I view them I'm using Preview App but it the images still look pretty poor when I upload them to the web.

Any thoughts or help would be really appreciated.

Thanks,

James