Usage metrics missing

Hi, I created a usage stats dashboard by following the process of saving a copy and removing the filters - this ran reasonably smoothly for a while, but skipped a bit of data, I get c 10,000 views a month from 350+ users, but I knew some users weren't having data captured as they weren't on the list of users and yet were asking me questions about the app content...

The problem today - no data since the 27th. I'm running a series of training courses and need to know who to focus on so need this resolved asap.

Any ideas? I've tried re-creating it, but still no new data post the 27th.

Thanks, Rachel