If this is fixed then it's good news

I'm not able to test this with the updated Impulse as I have the GalCivII packs installed, but by the sound of the OP my described events sound current, excluding todays Impulse update.
The problem is/was the prerequisite checks is/was applied when doing a "download and archive", and not only while trying to install,
making it impossible to download/queue all packs of GalCivII and similar, but instead requiring to install them to be able to download and archive the next.