I am fighting the Umbral Choir, but there seems to be a cloaked system that I cannot reach?! In the screenshot, there is an Umbral Choir fleet clearly "anchored" to a system (red circle). They are not moving either but replenishing their movement points. My fleet (white circle) has de-cloaking III and can see the ships, but not the system. Is this by design or a bug?

Thanks for your help!

Systems can't be cloaked, only Nexus around them. And you should see system node, if within discovered range.

Has to be a bug.