There is still a bug related to this.

I got to the stage where I needed to build the ascension gate and when I placed it on a planet all the build times (including for every other improvement/building) started to read "N/A".

Because the ascension gate is special I thought maybe the "N/A" reading was just a sign of the gate's specialness so I let a few turns go by. Then I wondered if I was failing because I no longer had a starbase examining an ascension crystal so I did that but nothing improved.

Anyway, finally, I read on the forums and I figured that checking all my colonies for Research Cloisters and destroying them would work. I found one, destroyed it, put the Ascension Gate on a different planet and sure enough I got a proper read-out of how long the gate would take to build. It built in the time I was told and I got my victory.

I would have felt pretty sick if another faction had stolen the victory in the turns I let go by.