Comment 3 for bug 1767886

The defaults for unspecified ldap_autofs_* settings changed between 1.15 and 1.16 it seems.

Here is a diff between the autofs section of the sssd-ldap page: https://pastebin.ubuntu.com/p/PJc5B9gwdr/

There are two settings for the map entry, and 3 for the autofs entry. You specified the rfc2307 schema, and just 3 out of 5 specific object classes and attributes overrides, leaving 2 to assume their default values for that schema type:

ldap_schema = rfc2307
# yours:
ldap_autofs_map_object_class = automountMap
ldap_autofs_map_name = automountMapName
ldap_autofs_entry_key = automountKey
# assumed default values when using rfc2307
ldap_autofs_entry_value = nisMapEntry
ldap_autofs_entry_object_class = nisObject

If you fix your config like this, it will work:
ldap_autofs_map_object_class = automountMap # your existing setting
ldap_autofs_map_name = automountMapName # your existing setting
ldap_autofs_entry_key = automountKey # your existing setting
ldap_autofs_entry_value = automountKey # new setting
ldap_autofs_entry_object_class = automount # new setting

I tested it with these automount entries: https://pastebin.ubuntu.com/p/z8fM4tvCzK/

Please let me know how it goes. If confirmed, I'll add an entry to the bionic release notes about this.