Since this version, Buffer depots are not picking up Request Depots, Supply Depots nor Transport Drones either.
I needed to change mines to use Request Depots to have supply in the area of my factory I needed.
Not ideal tho.
HTH

Can you provide a save game showing theproblem?

Here you have it. I left the character in front of a buffer that doesn't work
https://www.dropbox.com/s/0zt79svx4o5n9av/0.18-Outposts.zip?dl=0

thanks for the save, your base is very beautiful.

The problem is that, I change the way buffer logic works. I thought that it wouldn't make sense for the buffer to request items if there is only a few in the system, so I set the 'minimum request size' of buffers to be the request size. So they will only go pick up items if there is more than the request size in the system.

Requesters still use the other logic, where they will pickup small amounts if they are really empty.

Since there are only 11 depots in your system, the buffer depot is ignoring the supply depot, and not picking up anything