Version 53.0.2785.100 beta (64-bit)
Platform 8530.80.0 (Official Build) beta-channel samus
ARC Version 3249371
Firmware Google_Samus.6300.174.0

To repro:

1. Boot the device.  No need to sign in.
2. Press Alt+VolUp on keyboard.  In other words, press and hold ALt.  While holding Alt, press and release the volume up key.  Release Alt.
3. Press VolUp and see that volume indicator is not shows, volume remains unchanged.

What is the expected output?

In step 3, I expect the volume indicator to be shown and the volume to increase.

Note, once in this state, VolUp remains unresponsive until I press and release the Alt key (either Alt key).

Thinking this may be a hardware issue with my device, I checked another Samus and found the same behavior.