Sato-san,
If you click on the "Show Why Parts Were Not Found" button when you try to generate your above design, you can get some information on why the design creation failed. See the screenshot below:
The design fails because the calculated duty cycle exceeds the maximum 100% duty cycle.
While the LM25085 is capable of up to 100% duty cycle, WEBENCH calculations for duty cycle consider the rectifier diode voltage drop, high-side FET on-state voltage drop, and inductor DCR losses. In the case of Vin = 10.5V and Vout = 10.3V, the calculated duty cycle is above 100%. You will need to lower your Vout or increase your VinMin to get a LM25085 design to work. You might consider switching to the TPS54320 as well, which worked in WEBENCH with your design specifications.
-Kris
