No Matching Assets Found, even though there are matching assets

Hi there, I'm having a similar problem to the person in this thread.

I've got a bunch of images and PDFs uploaded via the Assets page, all under 10Mb. They are all marked as library items, some are tagged. I can browse them all and the filters are working as expected.

However, when I try to link to an asset from an editable textarea region, I get the "No Matching Assets Found" message no matter what I do. The filters and buckets and file types all appear as expected and switch views when I click them, but with only the "No Matching..." message in the display area. I get the same result whether I use the Picture or File tool (MarkItUp editor).

If I try to upload an asset from the popup window in the editable region, I briefly get the "uploading file" alert and the "Use Selected" button turns green, but the file never shows up. If I click the "Use Selected" button anyway, I get an error in the console of "TypeError: e[i] is undefined". Which makes sense because there doesn't seem to be anything to select yet.

I wasn't having any trouble with assets until just now when I wanted to start adding documents to the site. Images have been uploaded and used as usual for several months now.

Let me know if there's any other information I can provide or tests you'd like me to try. Thanks!

Template:

<perch:blocks>
  <perch:block type="single" label="Single session">
    <div class="session">
      <div class="session-meta">
        <p><strong><perch:content id="time" type="smarttext" label="Start time" required="true" /></strong></p>
      </div>
      <div class="session-group">
        <perch:content id="group" type="textarea" label="Talks" markdown="true" editor="markitup" />
      </div>
    </div>
  </perch:block>
  <perch:block type="double" label="Session plus workshop">
    <div class="session">
      <div class="session-meta">
        <p><strong><perch:content id="time" type="smarttext" label="Start time" required="true" /></strong></p>
      </div>
      <div class="session-split">
        <perch:content id="workshop" type="textarea" label="Workshop" markdown="true" editor="markitup" />
      </div>
      <div class="session-split">
        <perch:content id="talks" type="textarea" label="Talks" markdown="true" editor="markitup" />
      </div>
    </div>
  </perch:block>
</perch:blocks>

Diagnostics:

Summary information

    Perch: 3.0.10, PHP: 5.6.32, MySQL: 5.5.32, with PDO
    Server OS: Linux, cgi-fcgi
    Installed apps: content (3.0.10), assets (3.0.10), categories (3.0.10), perch_forms (1.9.1)
    App runtimes: <?php $apps_list = [ 'perch_forms', ];
    PERCH_LOGINPATH: /2017/perch
    PERCH_PATH: /home/ozewai59/public_html/2017/perch
    PERCH_CORE: /home/ozewai59/public_html/2017/perch/core
    PERCH_RESFILEPATH: /home/ozewai59/public_html/2017/perch/resources
    Image manipulation: GD
    PHP limits: Max upload 128M, Max POST 128M, Memory: 768M, Total max file upload: 128M
    F1: 3b606135b33e6a102526838f4152a807
    Resource folder writeable: Yes
    HTTP_HOST: ozewai.org
    DOCUMENT_ROOT: /home/ozewai59/public_html
    REQUEST_URI: /2017/perch/core/settings/diagnostics/
    SCRIPT_NAME: /2017/perch/core/settings/diagnostics/index.php