Can't seem to get the Milky-way crossing ending even though I've done all other endings.

I have just finished Vega and Altair after completing Promised Rinascimento and sending the D-RINE to the past, but all I got were the credits and the Vega & Altair ending, not the True Ending. Aren't I supposed to get the True Ending right after completing VA? What's the cause for this? (I'm playing the Steam version of STEINS;GATE 0 with CoZ's Steam Improvement Patch on Linux)