The enhancements to let players create routes without buying slots has been great, but there is a minor bug in editing slots, to finally buy the slots that were not bought originally.
Picture below shows an example. Route was without slots. Then, a slot was made available (by freeing it from another route). When editing the route to finally buy the slot, the system does not allow me to do it, if the slot at the other airport is not available.
There is a workaround. If I completely delete this route, and create one exactly the same, it will let me create the new route. So this bug is in Edit functionality.