I have been working on illustrator files containing linked images, which have been used often in different files in the past.
The ai file opens in CPU preview and cannot return to GPU (screenshot 1). Colors seem altered, very vivid.
I tried copying images from the CPU preview file to a new blank GPU preview file. When pasting the psd links all worked fine. When pasting the jpg image, the preview turns to CPU. Even if the image is deleted, the preview does not return back to GPU. Same test with another artwork and another jpg.
To conclude I cannot turn on the GPU preview, which some time ago was working. I have not received any error message that GPU Performance Features is not available. Other artwork opens normally.
The altered colors are caused by a bug with the color management that is related to Photoshop.
As for the GPU issue: please post a bug report on http://illustrator.uservoice.com
Maybe the engineers have an idea.