I had the same problem and was able to fix it. Under your SEO settings, go to ‘Other’. Under ‘Date Archives’ you’ll see ‘Meta Robots’. make sure the box where it says ‘Disable the date-based archives’ is NOT checked. Mine was checked automatically and when I unchecked it, it flushed my cache. when I checked my site and went to a monthly archive it displayed the page correctly starting with the oldest post of that month first and so on. Hope this helps!
