Outlook Signatures do not appears under Select signature to edit (4372560)

KDA is not supporting Roaming Signatures at this point and it's under consideration for a future release.

Workaround:

The Roaming Signature feature can be disabled by creating the following registry key of the current user.

Hive: HKEY_CURRENT_USER
Key Path: Software\Microsoft\Office\16.0\Outlook\Setup\
Value Name: DisableRoamingSignaturesTemporaryToggle
Value Type: REG_DWORD
Value Data:1

Finally, restart Outlook.