Used to have the issues with the category buttons switching around for no reason and "show all" broken URLs last week but these work fine now.
The missing thumbnail issue. It is starting to look like it will be permanent as nothing has improved over the two weeks since site update. CGT said that they were moving stuff to a new server and resizing all of the preview renders, which takes a lot of time. But at this point I doubt that this will be fixed. What bother me about the issue is that when you upload new previews instead of the broken ones, the main thumbnail gets messed up.
Tested this with one of my models and now the previews are visible but main thumbnail image shows the 3rd render instead of 1st for some unknown reason (Leaves Bunny Egg Cup 06). So I am not willing to re-upload previews for other broken products as it will just mess up the thumbnails.
And no, it is not browser related.