I believe I know what is causing this. There are 79 tag jobs in queue right now. My assumption is that these are the counts you are expecting to see increasing your numbers.
Right now, all those jobs are waiting on a culling job that happened to start about 2-3 days ago to finish before running. That job is set to delete 1.5 million documents and is going to hold up the tagging process until it completes.
Our system forces jobs to run linearly (one after the other) because otherwise it would create a 'race condition' to see who gets to the document first. This could lead to the system getting hung up on trying to tag a document that was just culled.
Once that cull job finishes, it will move those tag jobs through and should then update your tag counts. Unfortunately you won't see any statistics changes until that happens.