Cubase 15 – Input bus shows “No Source” even if correctly assigned (works in Cubase 14)

Cubase
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input bus
input bus1592×848 70.9 KB

channel input
channel input1808×888 168 KB

I’m experiencing a serious issue with audio inputs in Cubase 15 that does not occur in Cubase 14, using the same computer, same hardware, and same project.

Here is the situation in detail.

I’m using an RME Fireface UFX III.

In Cubase 14, everything works perfectly:

  • the microphone signal is present in TotalMix

  • the input bus is correctly assigned

  • the input channel receives signal

  • monitoring works and audio passes through inserts normally

When I open the same project in Cubase 15, the behavior changes.

In Audio Connections → Inputs, the input bus (for example “Mic ALEX”) is correctly created:

  • mono bus

  • device: Fireface UFX III

  • port: Mic input 11

However, when I look at the Input Channel in the Mixer, in the top-left corner it clearly shows “No Source”, even though the bus is assigned to a valid hardware input.

This is the key inconsistency:

  • Audio Connections shows the input correctly mapped

  • The Mixer input channel reports “No Source”

  • As a result, no signal reaches Cubase (meters stay at zero, monitoring is silent)

I tried all standard troubleshooting steps:

  • deleting and recreating the input bus

  • creating a brand-new empty project

  • resetting Cubase 15 preferences

  • disabling Control Room

  • disabling ASIO Direct Monitoring

The behavior does not change: the input channel still shows “No Source”.

To exclude the audio interface, I also tested with macOS Built-in Audio:

  • Cubase 15 does not even list the internal microphone inputs in Audio Connections

  • inputs cannot be assigned at all

This confirms that:

  • the issue is not RME-related

  • the issue is not project-related

  • the issue is not configuration-related

For comparison:

  • Cubase 14 on the same system correctly exposes and initializes all input sources (RME and CoreAudio)

  • Cubase 15 does not initialize audio input sources properly

From a technical point of view, it looks like Cubase 15 fails to initialize or attach the ASIO/CoreAudio input source layer, leaving input channels in a “No Source” state even when the bus is correctly defined.

I’ve attached screenshots showing:

  1. the input bus correctly assigned in Audio Connections

  2. the corresponding input channel in the Mixer showing “No Source”

At the moment, Cubase 14 is fully usable, while Cubase 15 is not usable for recording or live monitoring due to missing input sources.

I’d appreciate any clarification from Steinberg about:

  • whether this is a known regression in Cubase 15

  • or if additional steps are required to force input source initialization

Thank you.

2

Please make sure that Cubase 15 app is allowed access to audio inputs / microphones in the macOS security settings.

2 Likes
3

Solved! I hadn’t even thought about macOS microphone permissions. That was exactly the issue — great intuition, thanks!

1 Like