When Hummingbird creates cahce with Clear Cache button of post it is generating a post of somekind that is interfering with another plugin.
The BlogSocial plugin auto posts new posts to social media when a new post is published, but Hummingbird creates a cache file that is identical to a post which is making the conflict.
Blog2Social Developer suggested a solution
“there is a solution to prevent that the article is being reshared:
Simply deactivate the autoposter checkbox before using the ‘clear cache’ button to prevent that your article is being re-shared.
You can deactivate this feature by default in your blog2social settings for older articles (edited existing articles).”
Turning off a feature will be short term solution, the best solution will be to resolve the conflict.