• Summary / Title: When the Riftborn found an outpost it appears that they should be able to expend both Titanium and Hyperium to accelerate it's conversion to a full colony.  Titanium appears to work as intended, but Hyperium doesn't.
• Description: After founding a new outpost there are two button's/options available for the Riftborn to reduce the time needed to turn the outpost into a colony, either by spending Titanium or Hyperium.  If you expend the Titanium the time required for the outpost to convert is cut roughly in half.  If you try to also select Hyperium you are unable to do so.  There is a tooltip message that indicatates something like the outpost must be associated with a colony or something like that, but there doesn't appear to be any way to accomplish this.
• Steps to Reproduce: 1. Start new game as Riftborn.  2. Found new outpost. 3. Click on Hyperium button to accelerate outpost growth.
• Reproducibility: 5/5 - I found this repeatable on a few Riftborn games but haven't tested extensively.   It was on several difficulty setting, most recently endless. Galaxy size is usually small, random galaxy shape, medium level of pirate difficulty, 4 races total.  No mods, customizations or custom factions.
• Expected Behavior: I believe the intent is for the player to be able to accelerate Riftborn colony growth by using both Titanium and Hyperium with a 50% reduction in colonization time for both.
• Version: I didn't write this down, but can obtain if needed.  I'm playing on a Mac with the most recent version and all of the expansions up to Penumbra.  I'm playing the full release version, no development or test builds and no mods.
• Notes: Nothing more to add on this one except thanks for the continued work to polish this game, fix the bugs and general improvements.  If the overall balace and quality raises to the level of Endless Legend it will be a true classic.  We're not there yet, but with continued work I hope it will be there in the future.  It's pretty fun already, but there are still a number of things to improve which are hopefully in process.  Keep up the good work! :)
• Attachments: I don't have a save with this this bug, but if there is any trouble reproducting it please let me know and I"ll create one and add it to this post.

It is a known issue and has been reported multiple times.

Kuma did fix this bug within his mod: Enhanced Space 2 - Community bug fix and balance mod

In case you don't like the cool gameplay improvements coming along with Kumas mod (still work in progress), you can download my mod (Kuma allowed me to extract his bug fixes for vanilla game) here: BugFix v1.0

May the force be with you!