Low Yearly Archives and EE 4

Is anyone else using this add-on? It has worked just fine for me for years, but after upgrading to EE 4, it no longer seems to add new entries to the archive.

Example here: http://westeros.org/Citadel/SSM

There are entries for 2018, so there should be some months listed there, but they don’t show up.

I have not changed anything about the setup and the entries are setup the same way as the 2017 entries. The only difference I can think of is the fact that I upgraded to 2018, if there is some difference to how these entries are dated/stored/etc.