Steps to reproduce:

1. In Firefox, open this: data:text/html,<header>I am a banner</header><section><header>I am not a banner</header></section>
2. Examine the hierarchy for the "I am a banner" text.

Actual behavior:

For the parent, which corresponds to the header element that is a direct descendant of the document and therefore treated as a landmark, the role is spoken as "unknown". The developer info (NVDA+F1) is:

Developer info for navigator object:
name: None
role: ROLE_UNKNOWN
states:
isFocusable: False
hasFocus: False
Python object: <NVDAObjects.IAccessible.mozilla.Mozilla object at 0x056244F0>
Python class mro: (<class 'NVDAObjects.IAccessible.mozilla.Mozilla'>, <class 'NVDAObjects.IAccessible.ia2Web.Ia2Web'>, <class 'NVDAObjects.IAccessible.IAccessible'>, <class 'NVDAObjects.window.Window'>, <class 'NVDAObjects.NVDAObject'>, <class 'documentBase.TextContainerObject'>, <class 'baseObject.ScriptableObject'>, <class 'baseObject.AutoPropertyObject'>, <type 'object'>)
description: u''
location: RectLTWH(left=20, top=205, width=3800, height=47)
value: None
appModule: <'firefox' (appName u'firefox', process ID 15784) at address 4e9be50>
appModule.productName: u'Firefox Nightly'
appModule.productVersion: u'70.0a1'
TextInfo: <class 'NVDAObjects.IAccessible.IA2TextTextInfo'>
windowHandle: 590956L
windowClassName: u'MozillaWindowClass'
windowControlID: 0
windowStyle: 399441920
extendedWindowStyle: 256
windowThreadID: 1460
windowText: u'Firefox Nightly'
displayText: u''
IAccessibleObject: <POINTER(IAccessible2) ptr=0xa0120a4 at e72be40>
IAccessibleChildID: 0
IAccessible event parameters: windowHandle=590956L, objectID=-4, childID=-67110976
IAccessible accName: None
IAccessible accRole: u'header'
IAccessible accState: (0)
IAccessible accDescription: u''
IAccessible accValue: None
IAccessible2 windowHandle: 590956
IAccessible2 uniqueID: -67110976
IAccessible2 role: IA2_ROLE_LANDMARK
IAccessible2 states: IA2_STATE_SELECTABLE_TEXT, IA2_STATE_OPAQUE (5120)
IAccessible2 attributes: u'margin-left:0px;text-align:start;text-indent:0px;margin-right:0px;tag:header;margin-top:0px;margin-bottom:0px;xml-roles:banner;display:block;formatting:block;'

Expected behavior:

NVDA should not treat IA2_ROLE_LANDMARK as an unknown role, but read it as "landmark" or something sensibly similar.

System configuration

NVDA installed/portable/running from source:

Installed.

NVDA version:

All versions, including 2019.3alphas.

Windows version:

All Windows 10 versions.

Name and version of other software in use when reproducing the issue:

Firefox current release, beta, or nightly. IA2_ROLE_LANDMARK has been exposed since Firefox 65, see Bug 614572.

Other information about your system:

Also happens in Chrome, which also exposes this role.

Other questions

Does the issue still occur after restarting your PC?

Yes.

Have you tried any other versions of NVDA? If so, please report their behaviors.

Several, all yield the same result.