My guess is that there's an internal report describing the FLIR system and how the FLIR system works and how the internal workings of the FLIR system caused the visual phenomena. But that's all classified.

So they did the absolute minimum the Executive branch required them to do and left it up to the White House Press Secretary to explain it to the American public.

To me it reeks of the brass not wanting to have any more of their time wasted. There's a great scene in The Wire where the metro police, the harbor police, the state police, and the county sheriff arguing that a string of murders don't fall under their jurisdiction; it's your problem you deal with it etc, subverting the trope of the local cops fighting with the federal/state police (usually the FBI) that "this is my jurisdiction" or whatever. I think this is the same. The Executive branch (I'm 80% sure it was Trump, coulda been Obama, too lazy to look it up) demanded that they do a thing they didn't want to do, and then they dragged their feet and did the bare minimum, and in the process made a mess that now the Office of the White House now needs to clean up. (which they didn't, because they don't want to explain a classified sensor system in a public briefing either)