Automatic Branch Merging Git Flow Direction and Number of Merges

[Dusan Maksic]

I have gone through existing threads but they are either too old or are just related and to not resemble completely the question I'd like to ask.

So I am having trouble understanding what the workflow of automatic merging is. There is only one automatic merge performed, regardless of the number of release branches and conditions (semantic versioning in place, branches ordered). Documentation states that branches matching the name of the pull request target are added into the merge path and that there is a limit of 30 merges.

Example: branches are develop (development), release/1.0, release/2.0, release/3.0. 

I create a pull request from bugfix branch to release/1.0. After the merge, automatic merge merges solely to release/2.0 branch (not to release/3.0 and not to develop). Further (the same, pull req merged to 2.0 merges additionally only to 3.0). Why is that?