just installed Scanner Pro. After scanning and “share” a menu opens: beneath mail, photos etc there is a DT icon. Unfortunately, it only opens DTTG. I´m even able to browse my DBs and folders. BUT: Nothing happens after that. No optin to save. This seems useless to me 
You’ll find other threads here reporting same issue. I don’t know if DEVONthink ToGo or iOS–doesn’t matter. The work around is to save into the iOS File system, via “Files”, into DEVONthink ToGo folders. See @eboehnisch’s post just above yours.