Most probably it is due to the source and the file type, @mstfa
Is the photo taken by you?
I am asking because your profile is showing that some of the photos you added in Maps are not yours. This is a violation of the program but, back to your question, a downloaded image, not taken with the device where you are editing the photo, can be the reason for that message
However, the function is available only for photos taken with the device that I am using for uploading them.
On the meantime a would like to suggest you to delete every photos that has not been taken by you (the photos you used are very popular in the web) because the copyright violation is a serious issue in Google Maps, and can end in the removal from the Local Guides program