Facebook is doing heavy filtering on what is shown in the Facebook UI.
See this third party account of it:
https://blog.bufferapp.com/facebook-like-button
I can confirm if you go and view your full activity log it does show.
I think it's a case of Facebook not wanting confusing/spammy stuff coming up on feeds, and their social plugins produce a high degree of that. So the left hand and the right hand are fighting each other.
(Click to enlarge)
#2631 - Facebook Support: Like button commenting dialog doesn't work
See this third party account of it:
https://blog.bufferapp.com/facebook-like-button
I can confirm if you go and view your full activity log it does show.
I think it's a case of Facebook not wanting confusing/spammy stuff coming up on feeds, and their social plugins produce a high degree of that. So the left hand and the right hand are fighting each other.