M29w scanner: error during device I/O

Printer: HP MFP M29w
Ubuntu 19.04
hplip: 3.9.16

2 failure modes, both with an Error: "error during device I/O"

CASE 1
If I run either of the following commands (for example);
$ scanimage -d <devicename> > abc.tiff
$ scanimage -d <devicename> - x 10 -y 10 > abc.tiff

I get the error:
"scanimage: sane_start: Error during device I/O"

Note that with the above commands, the scanner head doesn't physically move.

CASE 2
If I use the xsane GUI, it seems as long as the predicted output file size is less than ~10MB, the scanner works. However, if the file size is greater than ~10MB, xsane shows a popup with:

"Failed to start scanner: Error during device I/O"

Note that with the above command, even when I get the error, the scanner starts its scan (physically moves the scan head in the scanner), but then fails with the above error.

hp-doctor states one warning:
"warning: Printer is not HPLIP installed. Printers must use the hp: or hpfax: CUPS backend for HP-Devices."

However, I did use hplip to install the printer. And I have tried multiple installs.

The above results are the same via wireless or USB connection.