Orichalcum Survey Assault - absence of zinc ore and orichalcum ore in mining results

Platform: Windows
ISP: Consolidated Communications
Type of Internet Connection: Optic fiber
Internet Connection Speed: 50Mbps
Date & Time: Mar. 16, 2017 10:22 PDT
Frequency: 15 mission attempts
Character Name: Antisense
Race: TarutaruF
World: Ragnarok
Main Job: Scholar, Lv.99
Support Job: Thief, Lv.37
Area and Coordinates: Leujaoam Sanctum assault zone
Party or Solo: Solo
NPC Name: None
Monster Name: None

Steps:

• I was attempting the "Orichalcum Survey" Assault mission in Leujaoam Sanctum, which requires the mining of an orichalcum ore to complete the mission with the temporary item "pickaxe" retrieved from the NPC Mulwahah
• Possible results from mining at various "Mining Points" that are situated around the zone are "You find nothing.", "Your pickaxe (temporary item) breaks!", "Mining is possible here if you have a pickaxe (temporary item).", "[Character name] finds a pebble!", "You can't mine here right now...", "[Character name] finds a zinc ore!", "[Character name] finds an orichalcum ore!"
• After at least fifteen attempts at this assault mission, where I attempt to mine at each Mining Point until the Mining Point disappears, then move on to the next one, I have accumulated 85 pebbles without ever obtaining a zinc ore or orichalcum ore from the mission, representing over~1000 attempts at mining where I did have the pickaxe (temporary item) and obtained either the result "You find nothing." or "[Character name] finds a pebble!"
• The complete absence of zinc ore during these series of assault mission attempts may indicate that the assault mission is not working as intended.