Most of the sightings were just people saying that saw a thing. They can’t know for certain what they saw. They weren’t there.
Like, even if they know there was a test in the right area at the right time, the witness could easily be looking the other way and not remember which direction they were facing. How often do you know which way it’s North?
Picture it as a conversation.
“I saw something round flying around all weird in the sky last night”.
“Well, we were doing tests on a weird round flying thing yesterday, so it was probably that”
They can’t give a more definitive answer. For all they know the person was drunk and saw a bat.