Ultraloq Smart Locks don't support the master key function.

For Ultraloq UL3/UL3-BT, Ultraloq Lever, and Ultraloq UL300, their cylinder is made by Ultraloq. They are the exclusive customization and different from the cylinders of any other locks.

For Ultraloq U-Bolt/U-bolt Pro and Ultraloq AutoBolt, they are using the Schlage type C cylinder, and it's pretty simple to replace it by yourself. You can follow this video to change the cylinder for U-Bolt/U-Bolt Pro.