I guess all “mysterious objects” have cloaking devices since there has never been a clear snapshot to view?
Given the size of the known Universe it is highly likely that Life exits throughout the Universe. Could some of those lifeforms be visiting Earth? Yes.
Every so often we are given a tiny, little bit of ‘sparse’ evidence that Aliens have visited, and/or exist on Earth. Usually in the format of grainy, low-resolution photos. The polar regions, deep oceans, and especially Antarctica, would be fabulous places to ‘hide’, but not for humans due to their very, very harsh environment.
Aliens would have extremely good cloaking devices to fully, and totally obscure their presence. Plus, ‘they’ would know when and where any military or scientific expeditions would be near enough to observe their movements. That’s basic strategy.
Knowing what I know about the inhabitants here, I’d cloak too.