First off, let me explain how close flags are handled:
When you flag an off-topic post, that flag goes into a queue: first the one visible to members with at least 10K reputation points, then if it hasn't been handled after a day, into the queue for moderators.
If anyone - a moderator or a normal user - votes to close the post, your flag is marked as handled, with a "helpful" status.
If five users (or one moderator) vote to close the post, it is closed. Note that this may happen well after your flag is marked as helpful if the first vote wasn't from a moderator.
If the post is closed as off-topic with the majority of voters (3 on most sites, 4 on SO) voting to migrate it, the post will be migrated.
In the example you linked to, the question garnered 4 "migrate" votes, but it was tagged latex with no other tags. Since every question on Tex.SE is implicitly tagged tex or latex, this means it would've migrated as an untagged question (which, when a moderator migrated it, did happen) - this situation prevents normal migrations from completing successfully. Your second flag resulted in a moderator migrating it, and it is currently untagged on Tex.SE.
Solution: make sure questions are well-tagged before flagging.
For the rest of your flags, you're either re-flagging them before enough close votes have accumulated, or before anyone has handled the first flag.
Solution: don't be so impatient. It takes time for questions to be closed. If you're able to garner 3,000 reputation points on SO, you can vote to close directly - this skips the first two steps above.