Lost civilizations, as such, are entirely plausible. Anything older than the Pharaohs might be knowable today only from stone and ceramic work, and there is no inherent need for a civilization to devote much effort to those. Anyway if they did, a later one might be able claim credit for the remains. (Cf. the copious pre-dynastic stone dishware.)

We now know Amazonians were domesticating trees at least 10kya, known today only from their major earthworks and from genetic traces in plant genomes.

Professionals can discuss any of that only in the context of evidence found and revealed, which might not be forthcoming for any number of reasons, past and present.