Windows 10 Playback through analogue mixer

Windows 10, Audacity 3.1.3
I think similar issues have been raised previously, but here is my version.
I run Audacity on playback through an analogue mixer as I need multiple inputs for theatre mics, sound effects and backing tracks.
On my previous Windows 7 laptop, with earlier versions of Audacity, never any problems when connected to mixer Line input.
Now, with a newer laptop with Windows 10, significant corruption of the output into an amplifier when connected to mixer Line input.
No problem through headphones connected to laptop, nor when connecting laptop directly to amplifier.
Also, clear output if connected to mixer via Insert.
Similar problems with a friend’s Windows 10 laptop and Audacity 3.1.3.
Problem occurred on both my mixers.
It seems the signal processing downstream of the mixer Line input, bypassed by Insert, is changing the input signal.
Is there a fix for this?

There’s a possibility that the new computer needs a “load” with a DC current path or a lower impedance load. You could test that with a Y-splitter to connect headphones and the mixer’s line-in at the same time.