I'm trying to get the large image card to work with a website. The metadata is being read correctly, but it's displaying the small summary card, instead.
My metadata:
<!-- Twitter Card -->
<meta name="twitter:card" content="summary_large_image">
<meta property="twitter:domain" content="volkischexe.com">
<meta property="twitter:url" content="/germania/index.php">
<meta name="twitter:title" content="Germania: An Introduction">
<meta name="twitter:description" content="...">
<meta name="twitter:image" content="http://volkischexe.com/res/cards/germania-intro.png?605a78eeba1aa">
<!-- OpenGraph Card -->
<meta property="og:type" content="website">
<meta property="og:url" content="/germania/index.php">
<meta property="og:title" content="Germania: An Introduction">
<meta property="og:image" content="http://volkischexe.com/res/cards/germania-intro.png?605a78eeba1ae">
<meta property="og:description" content="...">
<!-- HTML Meta -->
<title>Germania: An Introduction</title>
<meta property="og:url" content="http://volkischexe.com/germania/">
<meta property="og:image" content="http://volkischexe.com/res/cards/germania-intro.png?605a78eeba1b1">
<meta property="og:title" content="Germania: An Introduction">
<meta property="og:description" content="...">
<meta name="description" content="...">
<title>Germania: An Introduction</title>
Twitter seems to see my metadata correctly, too:

What am I missing here?
ETA: The validator doesn't show my cards correctly, but if I actually tweet them, they show up just fine. So there's something going on with the validator, but as long as my cards show up on Twitter, I'm good.
There are a few things that could be stopping Twitter from sharing a large card for your site:
Try replacing your code with this:
One thing (that may or may not be impacting Twitter) is the start of your page is missing DOCTYPE and some other stuff:
One thing with the Twitter card validator — sometimes is doesn’t rescrape your site when you click the Preview Card button. You may need to restart your browser (closed and reopened) and rescrape a couple of times to get it to load the new version.