can't access ADF to scan with hp 6978 and acrobat pro dc 2015

win 10 pro

new printer.  will copy on both sides using adf from printer panel.  will scan double side from ADF using hp sw.  hp scan doctor sw says everything is fine.

using WIA printer over network.

in acrobat i say scan both sides and it does not use the ADF, it uses flatbed.  data transfer is native, interface is hidden.  if i switch to native interface i can specify scan source, but it only scans 1 side.  acrobat says it has no updates.

please help.    my previous epson workforce did this effortlessly, but it died and epson removed the 2 sided option.

the hp 6978 was the only non-huge printer i could find with 2 sided automatic scanning.