Workaround I guess if I want games from that month is to use the web interface, although I haven't confirmed that they show there but on past experience they will.
Bug: missing month of archives for player when "threecheck" or other variant game present

https://api.chess.com/pub/player/halldorpalsson/games/2016/11
{"message":"Game type code \"kingofthehill\" is invalid.","code":0}

Dear @skelos, both archives are now again browsable. For your information this bug appeared 5 days ago and was affecting "non standard" live variations.

Thanks Andrea! There aren't that many players who play those variants, but I tripped across a few in those five days who'd at least experimented.

This is still appearing ... caching? This time I can use myself as an example:
https://api.chess.com/pub/player/skelos/games/2018/04
{"message":"Game type code \"threecheck\" is invalid.","code":0}
https://api.chess.com/pub/player/skelos/games/2018/06
{"message":"Game type code \"crazyhouse\" is invalid.","code":0}
https://api.chess.com/pub/player/johnlenin/games/archives
Bold above not found and returns a 404 error:
https://api.chess.com/pub/player/johnlenin/games/2017/11: 404 Not Found