Can't link 10 audio tracks

I'm trying to link my camera audio (4 tracks) plus external audio (6 tracks) to my video.

First, I'm delinking all previously linked media.

Then, I'm selecting all and control-L.

This usually works to link media. I can even use it to link two or three of the tracks, but not all of them.

Why? Is there something on my timeline preventing it? Is there a max # of linked clips? Linked selection is chosen.