We are having the same issue. We want migrate foliage from a 4.27 project to a 5.1 project. The buffers we wrote out for 4.27 do nothing in RMA Foliage for 5.1.
A side issue with 5.1 is we would like to use RMA to move foliage from sub-levels to the World Partition level, but when we do, the foliage lands in the wrong place, around 0,0 rather than out where it should be.
Thanks for your help!
-Donald