The firmware from comment #3 was distributed in linux-firmware starting with commit 5e6165a8705613646c9a5a282f0a7243fe5dafdc (https://git.kernel.org/cgit/linux/kernel/git/firmware/linux-firmware.git/commit/?id=5e6165a8705613646c9a5a282f0a7243fe5dafdc). Which corresponds to Ubuntu's linux-firmware package version 1.158, released on May 6, 2016. People who already had this firmware would not experience the regression, which could explain the mixed reports of reproducibility.