I just updated Lightroom to 2015.8 and it appears to render the frames in my filmstrip badly. Not the images, but the frames and their edges.
W10 pro with latest updates, Intel Core i7 5820K @ 3.30GHz, 32,0GB @ 1332MHz, 1TB SSD raid, large catalog with 133000+ raw files. I'm mentioning this because it doesn't appear on my surface pro 4 in a small catalog.
Thanks for reporting this issue.
Could you please try the steps below and let us know if the issue persists.
Hi Akash, the graphics card is always turned on (GTX 970) and did an optimization, a reboot of PC as well but it still appears. I must say: it only appears when I click "all photos" in my catalog, which is over 133K. When I click 1 folder, or even a year with 16K images in subfolders, then the problem doesn't appear. I guess it only shows up when over 100K images are loaded in the library. So I guess it's OK and not really an issue.