Help getting a loan in US while living abroad

[Steven Catudal]

My parents are currently living in Germany but want to buy a property in the Panama City, Florida. They plan to rent it out until they are ready to move back to the US. Their current income is in Germany but they file taxes in the US and hold US citizenship. They have been trouble getting a loan here in the US. 

Has anyone faced a similar situation and found a solution? They have great credit, are putting ~37%+ down, and their income more than covers their current living expenses and the new mortgage.