efiupdater does not update boot rom (firmware) during macOS upgrade

Although the log file looks pretty good, the firmware has not been updated. Here is a shorter version of the attached /var/log/install.log.

efiupdater[639:2651] `/usr/libexec/efiupdater -p "/macOS Install Data/.../EFIPayloads" -d ...`
...
efiupdater[639:2651] Perform update: file:///usr/sbin/bless (...)
efiupdater[639:2651] ---------- Running bless ----------
EFI found at IODeviceTree:/efi
Will need to copy 8523776 bytes to EFI system partition
GPT detected
No auxiliary booter partition required
Preferred system partition found: disk0s1
Returning booter information dictionary:
{
    "Auxiliary Partitions" =     (
    );
    "Data Partitions" =     (
        disk2s1
    );
    "System Partitions" =     (
        disk0s1
    );
}
Mounting at /Volumes/bless.lLAP
Executing "/sbin/mount"
Returned 0
Creating /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE if needed
Deleting previous contents of /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE
Deleting /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE/MBP111.scap (8520304 bytes)
Opened dest at /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE/MBP111.scap for writing
preallocation not supported on this filesystem for /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE/MBP111.scap
/Volumes/bless.lLAP/EFI/APPLE/FIRMWARE/MBP111.scap created successfully
bless: Disk at mount point (/Volumes) doesn't appear to be backed by a TDM system, using running device identity
Relative path of /Volumes/bless.lLAP/EFI/APPLE/FIRMWARE/MBP111.scap is \EFI\APPLE\FIRMWARE\MBP111.scap
IOMedia disk0s1 has UUID 74AF37C8-2281-4BE2-ABAE-2141A8EA455F
Executing "/sbin/umount"
Returned 0
Write to RTC: 0
Setting EFI NVRAM:
{
    "efi-apple-recovery" = "<array>...</array>";
}
efiupdater[639:2651] ---------- bless complete ----------
efiupdater[639:2651] bless returned: 0
efiupdater[639:2651] Background color default set successfully
efiupdater[639:2651] Success. Reboot required to apply firmware update
efiupdater[639:2651] Exit status: 0 (Success: reboot to apply firmware update)
OSInstaller: /usr/libexec/efiupdater finished with status: 0
OSInstaller: Writing firmware update installed cookie (/Volumes/Macintosh HD - Data/macOS Install Data/.FirmwareUpdateInstalled)
OSInstaller: GetModel: model = MacBookPro; major rev = 11; minor rev = 1
OSInstaller: Machine appears to be AR capable
OSInstaller: Could not get VEK state for /dev/disk1s1, err=22
OSInstaller: Pre-EFI tool APFS stash: SUCCESS
OSInstaller: GetModel: model = MacBookPro; major rev = 11; minor rev = 1
OSInstaller: Machine appears to be AR capable
OSInstaller: Stash commit success
OSInstaller: Pre-EFI tool stash commit: SUCCESS
OSInstaller: Attempting to flush install log back to IA.log
OSInstaller: ia.log is missing from mutable product, creating at /Volumes/Macintosh HD - Data/macOS Install Data/ia.log
[reboot]
Launching the Language Chooser...

The boot rom is still on 151.0.0.0 instead of 157.0.0.0.