Also, it works incredibly slow when you have thousands of tasks. And when you make a subitem through a pop-up window, it doesn’t automatically create a connection in hierarchy view.

Zenkit is better than everything else I tried, but it really needs more automatics, deeper mathematical filtering settings, maybe allowing some user scripts, programming. Look for the Bulter addon on Trello – it has fantastic opportunities (but because of really silly limitations even on business subscription it’s just unusable for me) – I really believe Zenkit can make much better because of the Zenkit idea itself. The ideas and the core are great and open up almost unlimited opportunities, but the realization often severely limits them.