syndication feed cut-off

Dear Sirs:

If I understood the documentation correctly, even though I have “full post” checked on syndication send, but then use the “split post” command when writing posts, only that portion up to the split should be sent out over the feed with a link back to read the rest. I have encountered at least one feedfinder however “Pluck?” that has the entire posts displayed anyhow. Any suggestions as to why this is occurring and how to correct it? Thank you.