Hello, I'm seeing the exact same issue described here.
Essentially, I can't access the side quests in Central & Western Thanalan. I stopped leveling my CNJ once I hit level 15 and started leveling a GLD. As a GLD I completed all the side quests in Ul'dah, Scorpion Crossing, & the Silver Bazaar. Once I completed the quests at the Silve Bazaar I noticed that all the side quests in Central Thanalan had vanished. They were there before but now they are gone. At that time I had not completed a single side quest in Central Thanalan. I was able to complete two quests in Horizon as well.
At the time I still hadn't completed the main scenario quest "The Gridanian Envoy." I still needed to speak with the Flame General.
Any ideas? I haven't seen this problem in Lominsa or Gridania yet. I'm worried that I will have the same problem in Eastern & Southern Thanalan, or with higher level quests in the same zones.
Completed Sidequests
Ul'dah
No Lady is an Island
The Great Gladiator
With Open Arms
Due Diligence
Motivational Speaking
Gil for Gold
Unholy Matrimony
Decisions, Decisions
Vox Populi
A Luxury Long Lost
The Wealth of Nations
Beet-red Beetles Beat Red
In the Name of Science
Tougher than Leather
Western Thanalan
Nor Rain nor Heat nor Gloom of Night
A Dab'll Do Ya
Ticked Off
I Believe You Can Fly
Reasonable /Doubt
Greasing the Cogs
Getting Your Bearings
So Close Yet So Far
Tackle the Problem
Search and Seizure
By the Toe
For Their Eyes Only
Missing Side Quests
Central Thanalan
The Slaying of the Shrews
Listen to Your Fish
The Tasting of the Shrews
Bloodied and Bowed
Sometimes the Old Ways are Best
In the Court of the Rat King
Need Not Apply In Person
Fringe Benefits
Alternative Medicine
Western Thanalan
Simply the Hest (Guildhest Quest - Probably not relevant)
No Tool Gets Left Behind
The Scent of a Mongrel
This Fishwife's Life
Angling Ankle-biters
Lominsan Rubbish