I believe the archive function was altered to reduce the load on the server.
It's not a bug as far as I'm aware... To view older games you may set certain search criteria such as a time period in which a game was played, whether you won/lost, and the variant that was played.
Hope this helps somewhat- if anyone has anything else to add feel free to.
Before, I could view all of my 4PC games when searching the archive using "All Time" for the date range. Now, I am only seeing 40. Is this an update? How can I see older games?