Shutdown delay with LVM and disk encryption (SysV, buster)

[Bill Brelsford <wbrels@k2di.net>]

My 64-bit buster installation was created using its installer, with
/ and /home partitions in an encrypted logical volume (sda3_crypt).
On shutdown, it pauses near the end with

  Stopping remaining crypto disks... sda3_crypt (busy) sda3_crypt busy...

The busy messages continue for about 30 seconds, after which it
indicates "Failed" in red (I think, it happens fast) and shuts down
in a second or two.

If I change to systemd, shutdown is fast (no delay).

This appears to be similar to earlier bugs, e.g.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=792552,
except that they hung indefinitely.

Anyone else seeing this?  Any suggestions or workarounds (other
than systemd)?  Thanks..

-- 
Bill Brelsford
wbrels@k2di.net