I had my previous topic closed. After more testing, I've found the culprit is the Major Tech Accelerator. Here's the picture of what's happening:
Mk 12 VR to Mk 14 UR
At Mk 12 Very Rare with Omega/Major Tech Accelerator, Chance of Quality Improvement is 20% (5% for VR and 4x from Omega). The item turns Ultra Rare at Mk 13 with a 10% Chance of Quality Improvement (2.5% for UR and 4x from Omega). Upon reaching Mk 14 UR the chance drops to 5% (2.5% for UR and 4x from Omega does not equal 5%).
Major Tech Accelerators becoming detrimental to the upgrade process at Mk 14 seems broken to me.