Hello, do you remember this previous topic?
https://www.8theme.com/topic/annoying-flickering-effects-in-portfolio-after-last-upgrade/
Last time you wrote:
The problem was fixed in woopress/js/plugins.js file. You can download this file from the test site and replace it on your main site. The fix also will be included in next theme update.
Please note that after the last update of the theme (4.3) the miniatures of the Portfolio page were flickering again and I needed to copy the plugins.js file again to solve.