When I create certain objects - for example:

$mysqli = new mysqli('localhost', 'root', '', 'mydatabase');

then if I examine $mysqli in "Immediate" debug in PHPEd, I see

: object(mysqli) =
affected_rows: undefined = NULL
client_info: undefined = NULL
etc.
server_info: undefined = NULL

All fields are NULL.

But if I ask for specific fields, I can see the contents, and the contents are no longer NULL:
$mysqli->server_info
: string = 5.1.41-community-log

Why do I have to ask for specific fields? Most objects just show them.

And is there a way to see them without specifying them, as in
object(mysqli)

var_dump seems to work sometimes, and not others

Try serialize($mysqli) and you'll see exactly the same NULLs. So debugger did not fool you -- it was content of the object properties.
I'll check why var_dump works differently.
As of $mysqli->server_info expression, I'll check that too.
Next time please submit such reports using Contact Us form, please.

I presume that you are asking me to use the contact form if I am reporting a bug.

I thought it was something stupid that I was doing wrong!