My daughter said "These photographs are concerning". Her intention was to convey that they were disconcerting, or alarming in some way. My impulse was to correct her, but then I doubted myself and thought that perhaps this is a legitimate use of the word. The two online dictionaries I looked in don't have secondary definition that fits the bill, so, I'm now once again reasonably certain that my impulse was correct, but I'd be curious what you folks think.
One of the OED’s definitions of the adjective concerning is
That gives cause for anxiety or distress.
That would seem to cover your daughter’s use. Whether using the word in this way is an effective means of expressing her meaning is another matter.