Only 1 Build agent active, despite having 6

Description of issue:
We are trying to build our game in 3 different versions, for 4 different platforms each right now, resulting in 12 builds.
We have 6 concurrent builds enabled on our organization and it has worked like a charm for ~3000 builds so far. Since today however, only 1 build agent seems to be doing work for us.

Unity version:
2019.2.0f1

XCode version:
-

Source control:
Git with Gitlab

Local build platform:
Windows

Build target:
Android, Winx86, Winx64, WebGL

Relevant plugins being used (i.e. Google Play Game Services, other plugins that may perform automatic post-build behaviors)
-

Build log (relevant chunk):
No build log.

Does it build locally from a fresh checkout?
The building worked fine yesterday, it only started acting up today. All we changed was adding a scriptableobject. We think that the issue may lie in the build service.

Here's a screenshot of our building queue:

 

We only have 2 agents but none of them runs since 2 hours

 

I see. Thanks for sharing your issue!
That solidifies our belief that it's an issue on unity's service side.

We've just had a second agent start building. So it seems it does work, it just takes a long time to get an agent.

 

Our builds are running now, thanks a lot for sharing that link, I wasn't aware of that page!