Lender tells me it will be difficult to get a mortgage on residential/commercial zoned property. Help me understand.

3500 square foot home under one roof. 2000 square feet residential living are with 1500 square feet of the home converted into a dog boarding kennel. On 18 acres of land. 425K asking price. real property and equipment only. This is not a business purchase.

Lender tells me that it is going to be difficult to get this property to qualify because of how it is set up. Lender didn't explain. He said he is on vacation and I can reach him when he returns in two weeks. I can pay cash for the property, but I would rather not.

Why would a property have be hard to qualify?