Time Machine not keeping hourly backups.

My Time Machine backups don't seem to be working correctly. It doesn't appear to be keeping hourly backups. When I enter Time Machine and look at the backup from just one hour ago, the newest file is from several weeks ago, not one hour ago.

Same thing with monthly backups. At a certain point, the backup history skips several months.

I've scoured the internet but can't seem to find anyone else with this problem or a solution.