Setting "Crossmix" to 0 will block

[audiofranky]

I observed that when I set the "Crossmix" handle on the right side of the window to 0%, the process stops outputting any audio at all, and the load on one of my CPU cores goes up to 100%. JACK starts reporting hundreds of xruns from that moment on.
If I increase the crossmix value to >0%, it will recover after ~1s, and audio output continues. Denormal problem?

Generally, I noticed that adjusting the crossmix value will always cause xruns during a short moment of high CPU activity ("by design"?).

System: aether commit 5a1a7f, Host Qtractor 0.9.25, OS: Linux Mint "Una" (kernel 5.4.0), gcc 9.3.
jackd is set to 48000Hz, 128 frames/period, 2 periods/buffer.

By the way, thanks for Aether! I like it.