Problems with hp-toolbox (hplip 2.7.10-5)

["Todd A. Jacobs" <nospam@codegnome.org>]

After a recent upgrade to a recent version of hplip and hplip-gui, my
Debian Linux system can still print to the printer, but I have lost the
ability to use hp-toolbox. The CUPS printing system sees the printer,
says it's online, and prints just fine, but any attempts to use the
toolbox, or utilities like hp-sendfax, now tell me "No Installed HP
Devices Found."

Since I can print to it, the problem seems likely to be in the way
hp-toolbox is reading (or not reading) the CUPS configuration, right?
Has anyone else experienced this? How can I troubleshoot this further?

-- 
"Oh, look: rocks!"
	-- Doctor Who, "Destiny of the Daleks"