Well I've done the update (that was a scary one!!) and it still works ok here, I'm now on version 19042. I might need to compile a new version to get to the bottom of this issue. If you're happy to take a newer version, can you drop me an email? Contact details are in the Readme.txt file included with the distribution. Thanks ;o)
Thanks for looking into it. I found there was a problem in my system configuration that caused the game to load the wrong MonoGame.Framework.dll (i.e. not the one from the game directory). When I fix that it works perfectly. Sorry for the false alarm. Fantastic game, and love the art style! Can't wait to buy the full version. :)