Just back to let you know that this still is not fixed for me after the recent patches.
In fact learning the teleportation skill via skillbook also does not seem to work after the ability is modified in any way. Teleportation scrolls still work with modifications applied.

Could this issue be fixed by creating a new, modified version of the teleportation skill and linking it to the skillbook and scrolls while leaving the original freefall skill untouched?