I’m able to like and unlike your post just fine, it might be important for the users who originally liked your topic to post their browser details like it says in the About the Web Bugs category post.
Proof that I can unlike your post just fine, even after reloading:
https://i.gyazo.com/c1d4991b9fb426f02317ce81204aa0de.mp4
As far as I know, the badge rewarding process might not work for topics in private categories, since it would be confusing for users without permissions to see a topic they can’t view on your profile. This seems to be true with Roblox’s badges, since the New Member FAQ has way more than 10 likes (50 likes when I typed this) and the badge is not shown on the account’s profile.