Unable to comply - here is what I get when I run soimple-scan from the command line - it never fires the scanner properly and all I get is errors:

$ simple-scan -d
[+0.00s] DEBUG: simple-scan.vala:1720: Starting simple-scan 3.36.3, PID=1139752
[+0.00s] DEBUG: unsetenv() is not thread-safe and should not be used after threads are created
[+0.02s] DEBUG: _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ‘gio-vfs’
[+0.05s] DEBUG: _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
[+0.08s] DEBUG: app-window.vala:1906: Loading state from /home/admar/.cache/simple-scan/state
[+0.08s] DEBUG: app-window.vala:1885: Restoring window to 2506x1175 pixels
[+0.15s] DEBUG: scanner.vala:1539: sane_init () -> SANE_STATUS_GOOD
[+0.15s] DEBUG: scanner.vala:1545: SANE version 1.0.29
[+0.15s] DEBUG: scanner.vala:1606: Requesting redetection of scan devices
[+0.15s] DEBUG: scanner.vala:828: Processing request
[+0.50s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+7.16s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+7.52s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+7.57s] DEBUG: scanner.vala:341: sane_get_devices () -> SANE_STATUS_GOOD
[+7.57s] DEBUG: scanner.vala:353: Device: name="hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662" vendor="Hewlett-Packard" model="OfficeJet_4650_series" type="all-in-one"
[+7.57s] DEBUG: scanner.vala:353: Device: name="escl:https://192.168.1.107:443" vendor="ESCL" model="HP OfficeJet 4650 series [A67ED8] SSL" type="flatbed scanner"
[+7.57s] DEBUG: scanner.vala:353: Device: name="escl:http://127.0.0.1:60000" vendor="ESCL" model="OfficeJet 4650 series [TH7B64F03Z0662]" type="flatbed scanner"
[+7.57s] DEBUG: scanner.vala:353: Device: name="escl:http://192.168.1.107:8080" vendor="ESCL" model="HP OfficeJet 4650 series [A67ED8]" type="flatbed scanner"
[+7.88s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+9.02s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+11.78s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+14.75s] DEBUG: simple-scan.vala:1536: Requesting scan at 300 dpi from device 'hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662'
[+14.75s] DEBUG: scanner.vala:1674: Scanner.scan ("hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662", dpi=300, scan_mode=ScanMode.COLOR, depth=8, type=single, paper_width=0, paper_height=0, brightness=0, contrast=13, delay=3000ms)
[+14.75s] DEBUG: scanner.vala:828: Processing request

(simple-scan:1139752): Gtk-WARNING **: 17:22:33.786: Calling org.xfce.Session.Manager.Inhibit failed: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method “Inhibit”

(simple-scan:1139752): Gtk-WARNING **: 17:22:33.787: Calling org.xfce.Session.Manager.IsInhibited failed: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method “IsInhibited”
[+14.76s] DEBUG: scanner.vala:889: sane_open ("hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662") -> SANE_STATUS_IO_ERROR
[+14.76s] WARNING: scanner.vala:893: Unable to open device: Error during device I/O
[+15.30s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+20.42s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+35.67s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+40.79s] DEBUG: autosave-manager.vala:265: Waiting to autosave...
[+40.89s] DEBUG: autosave-manager.vala:287: Autosaving book information
[+41.09s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+43.99s] DEBUG: simple-scan.vala:1536: Requesting scan at 300 dpi from device 'hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662'
[+43.99s] DEBUG: scanner.vala:1674: Scanner.scan ("hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662", dpi=300, scan_mode=ScanMode.COLOR, depth=8, type=single, paper_width=0, paper_height=0, brightness=0, contrast=13, delay=3000ms)
[+43.99s] DEBUG: scanner.vala:828: Processing request
[+44.00s] DEBUG: scanner.vala:889: sane_open ("hpaio:/usb/OfficeJet_4650_series?serial=TH7B64F03Z0662") -> SANE_STATUS_IO_ERROR
[+44.00s] WARNING: scanner.vala:893: Unable to open device: Error during device I/O
[+44.57s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+48.95s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+53.25s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+91.31s] DEBUG: app-window.vala:1981: Saving state to /home/admar/.cache/simple-scan/state
[+92.43s] DEBUG: autosave-manager.vala:201: Deleting autosave records
[+92.43s] DEBUG: scanner.vala:1702: Stopping scan thread
[+92.43s] DEBUG: scanner.vala:828: Processing request
[+92.44s] DEBUG: scanner.vala:1713: sane_exit ()
$ 

This never happens when I start the scanner from the menu, although it does tend to happen after I've left the scanner and app sitting idle for a wihle.  I never timed it.

Other suggestions?  I'm here to help.