Just wanted to repeat my previous conjecture that we would not recognize an intelligence sufficiently different from ours as one. After all, any human actions can eventually be reduced to the underlying physics. And the problem of detecting agents without knowing their goals in advance seems to be an open one, as far as I can tell, attracting little interest.
Thus the "Great Filter" is just our blindness to all other forms of agency.
An Article on Motherboard reports about Alien Minds by Susan Schneider who claiThe Dominant Life Form In the Cosmos Is Probably Superintelligent Robots. The article is crosslinked to other posts about superintelligence and at the end discusses the question why these alien robots leave us along. The arguments puts forth on this don't convince me though.