I have completed the Daily Jewelry Crafting Writ each day since Summerset released. For the last week each Writ has granted no Inspiration in Jewelry Crafting. I started tracking Inspiration values once I noticed this.
I am 50 in all crafting skills except Enchanting. Oddly enough completing a JC Daily Writ was leveling Enchanting, not Jewelry Crafting.
Here are some completion examples:
Jewelry Crafting Level 22:: 4866 -> 4866 (0 Gain)
Enchanting Level 39: 82,343 -> 90,143 (7800 Gain)
Jewelry Crafting Level 29: 30,155 -> 30,155 (0 Gain)
Enchanting Level 40: 70,387 -> 83,387 (13,000 Gain)
Jewelry Crafting Level 33: 64,934 -> 64,934 (0 Gain)
Enchanting Level 40: 109,921 -> 122,921 (13,000 Gain)
And just this morning...
Jewelry Crafting Level 48: 31,845 -> 31,845 (0 Gain)
Enchanting Level 43: 155,473 -> Level 44 19,513 (20,800 Gain)
Inspiration may or may not go to Enchanting exclusively. It may go to any skill that isn't 50. Finding out what happens with other players may help see the entire problem.
I am "fairly" certain the Pewter level of Daily Write gave me inspiration... I have one note of gaining 2600 at JC 4. Unfortunately I wasn't keeping detailed records initially. This bug may kick in after putting a Skill Point in Engraver, which starts Copper-based Writs.
Confirmed with one other friend he's getting no Inspiration from completing the Daily Writ. Decided to post here in case others are seeing this. If you can confirm this behavior please post a /bug report in game. Hopefully this issue will gain some traction. After three patches since Summerset's release this seems like something that should be fixed.