Trying to import WebM videos and maintain Uktra HD resolution - help?

Hello! I've been trying to use Ultra HD WebM files in Adobe Premiere with no luck. I can convert them to mp4 with VLC but I lose the ultraHD, and I can import them with Fnord which also loses the Ultra HD resolution. Both of these drop ultra hd resolution to regular old HD, and I can't find a setting to fix it. Can anyone help?