I had been used 2 context menu with this command
Add to WMP = Add Selected files in to Windows Media Player Playlist (When WMP is my Default Music Player)
ContextMenu VERB=enqueue
Play in WMP = Play Selected files in to Windows Media Player
Most likely another program took over the file type and WMP's menu items are no longer there. It's unlikely to be anything related to the last Opus update.
Try ContextMenu VERB="Play" LOOKUP in case that helps.
It's still working fine here both with and without the LOOKUP argument, but that can help sometimes.
It's also possible another handler is getting in the way or the WMP registration is damaged in some way. Your "Play" menu item is called "Play with Windows Media Player" here, so something is different between our machines. You can usually repair WMP's registry settings by re-assigning the relevant file type to it.
Using a media player with a proper command line interface so you aren't restricted to its context menu items is another option. Then things are a lot easier.