I did not delve into why my posts were not rebaked so it remains a mystery. If somebody encounters this problem and wants to rebake manually their posts this is how i did go about it:
Enter Rails console:
cd /var/discourse
./launcher enter app
rails c
And I did run this script:
posts = Post.where ("cooked like '%lazyYT%'")
posts.each do |p|
p.rebake!
sleep 1
end
One post per second is slower than I would like, but I wanted to be extra sure that I will not hit any YouTube limits if there are any. For 12 000 posts it was not that bad of a wait.