I could not add people to an image

I had "Redwood forest exploration" as my main keywords and wanted to add a couple hikers into the illustration but it spat out an error, "This image produced an error. Please try again." Perhaps it is a safeguard from the AI feeding inappropriate imagery but I wish the messaging was clearer as to why it was not working. I tried "hikers in redwood forest" and "Redwood forest explorations with hikers" but all variations produced the same error.