Thank you for your question.
Unfortunately this not depends from OS Comments and Sharing - Joomla social share module. For share images with help Facebook your links need to be flushed before they start working properly. Go to developers.facebook.com/tools/debug,
paste your link there, press debug, and then try again sharing it on Facebook. It should work.
If not, give it a few hours and try this again.
More how Facebook works with sharing you can find below