Issue with AI generative fill

Hi everyone, here's my problem, just starting to play with new AI features in Photoshop and it's very promising but I encounter an issue when trying to generate a background to my image with a simple prompt in the generative fill as "mountains", it's ok at first sight but it emulate also a part of the existing image, so I have portion of architecture with the generated background which is incorrect, any idea to solve this problem ? 

Thanks in advance ! regards.