Hi Steve,
As far as we have seen so far, this is an issue that occurs intermittently, refresh of the page usually works with no issue as indicated John above.
In our experience this is usually related to network/performance, so if you also witness slow Clarity / network response times, I would recommend you to look into it, as it will likely solve this issue as well.
Please also note if it happens more in peak times, etc., and whether it's always one specific page that gets the issue, and is it occurring with all browsers. This will be helpful to get more insight on the root cause.
Hope this helps.
Kind Regards
Nika Hadzhikidi
CA Technologies
Principal Support Engineer