It's been pretty packed for several years - AHS moved in just as CN was moving out. Maybe you're thinking of the City of Edmonton that moved in a few years ago?
It is nearly fully leased right now with the exception of some ackward shaped space on floors 5 (partial floor only as the parkade goes up there) and 15 (only floor with elevator lobby on both sides which gives quite a bit less useable space on the floor).
The building badly needs renovations though.