A/B Test not working

An A/B test with redirection was created and the code embedded on the page. Almost no data is displayed in the report though.
For first like three weeks after the test was created, only a couple page calls were registered in the report. A lot less then actual page calls.
The test itself seems to work on the page. When opening the article in an incognito browser, the page is redirected half the times, just like it should.
Additionally there is a problem while editing the test, in the Target Pages tab. The first two input fields for the rule are empty and you cannot choose anything (“URL”, and “starts with”). Every like third time when on this page everything is displayed right. The URL itself is always there.
Earlier this week I created an exact same test (with only an additional letter in the title, everything else exactly the same), and for a day both tests worked. I got data for a day and as everything seemed to work I deleted the second test. Now the first one stopped working again.
I really have no idea what the problem is…