Unable to Desynth or GC seal exchange certain Landking gear

Date & Time: October 30, 2019
Frequency: Constant
World name: Behemoth
Character name: Pixel Eigengrau
Retainer name: N/A
NPC name: Storm Personnel Officer
Monster name: N/A
Class/Level: Any
Party or solo: N/A
In-game time: Any
Area and coordinates: Any
Housing: N/A
Steps:
1. Gear Affected: Landking's Fishing Rod, Landking's Turban, Landking's Coat, Landking's Gloves, Landking's Bottoms, and Landking's Shoes

2. Attempted to exchange gear for Grand Company seals but they do not appear on the Expert Delivery list. (Verified items were in my inventory)

3. Waited until this patch (5.1) to try desynthing them under the changed criteria, but it is still not an option. Had no issues with Handking gear nor the Landking accessories- just the gear listed above.