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Add-on is constantly giving me "No subtitles found".

Am I the only one with this problem?

No you're not. I've been experiencing this for the last couple of weeks. I won't post a full log for privacy reasons and partial / redacted logs aren't allowed, but the debug log basically only says No subs for "Series 01x01" found despite there being plenty of results. I also noticed that the page being used (https://www.addic7ed.com/search.php) is just a blank page when opened in browser if you haven't logged in with your Addic7ed account. There's also a recent announcement on the site that states:

Some pages now require you to be logged in. If something doesn't display as usual, try logging in first!

So I'm guessing it's related to that. It's an effort to reduce server load probably. They also have Captcha which prevents logging in with 3rd party apps.