Tested a couple times now and the behavious seems reproducible. On the first akregatormigrator run, the tool just waits in the event loop doing nothing (tried attaching gdb to the pid, cont/break/bt the frames are always the same) No activity on the akonadi side either. The situation usually improves after quitting the migration app and running it again
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of akregator (version 5.0 or later, as part of KDE Applications 15.08 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.