Hi @anlino,
I have tested this on multiple browsers and agree it does seem to be a browser specific issue. I can’t tell if this is down to browser settings or just version though as it works for me on Firefox 78 but not 79.
I think it shows past posts if the browser decides to retrieve the page from its back/forward cache and doesn’t if the browser decides to reload the page. I’m not sure why my browser doesn’t use the bfcache.
For now I have ‘fixed’ it by increasing posts/page (they are lazy-loaded anyway); I assume a hard redirect to page 1 would also work as a fix.
Dom
