Global Secure Access (GSA) Private Access client (macOS) blocks Apple Sidecar connection establishment over USB-C; established sessions survive client re-enable

With the GSA client enabled (Private Access and M365 profile only), Apple Sidecar fails to establish a connection from the Mac to an iPad connected via USB-C cable (iPad used as a secondary display). When the GSA client is disabled, Sidecar connects successfully. Once the Sidecar session is established, re-enabling the GSA client does not break the existing connection — it remains stable. This indicates interference with the Sidecar connection-establishment/discovery phase rather than the steady-state data path.

Steps to reproduce

1. GSA client enabled, Private Access profile active.
2. Connect iPad to Mac via USB-C cable.
3. Attempt to use iPad as an additional display via Sidecar.
4. Result: Sidecar fails to connect.
5. Disable the GSA client.
6. Re-attempt Sidecar → connects successfully.
7. Re-enable the GSA client → existing Sidecar session remains connected and stable.

Expected behaviour Sidecar over USB-C should establish normally with the GSA client enabled.

Is this a known issue? Is there a workaround that doesn't involve disabling the GSA client?