Seems we are missing some. Like Grinson Stoe. Got the quest earlier this week, but now he has disappeared. Quest givers in TB do not show any quest available. Only 1 in Main City and two left in Margie Palace.
Found this posted by Slipmat in another thread, hope it helps.
At Guild level 25 the only way now to get and turn in Guild Quests is through the Guild Questmaster which must be placed in the Guild Dimension, you can buy this NPC from level 22 onwards.
If by some strange chance your Guild doesn't have one yet, simply jump into another Guild's Dimension that's level 22 or higher and you can cash in your quest with their Questmaster