Disabled tasks in composite builds

Tested on:
Eclipse IDE for Java Developers
Version: 2018-12 (4.10.0)
Build id: 20181214-0600
Buildship 3.0.1

I have imported the same composite build project in Eclipse and IntelliJ and the result is quite different. In Eclipse I cannot run any taks configured in the included builds. In IntelliJ that works fine.
I have noticed that this problem occurs “some time” after the projects have been worked on.
Removing them from the workspace and reloading them does not solve the problem.
Any idea?
See the pictures


The weird thing is that if I close the one of the eclipse project included as build, the tasks become active.

Is this the expected behaviour?