Launcher 'Versions' drop down is empty, can't create new installation

In the launcher, anything dealing with the 'Version' drop-down for the Java edition of Minecraft is blank. For example, if I click on "New installation", I get the following screen (I don't know how to put an image inline, see attachment.) The "Version" drop-down is blank and I cannot click on it, which means I can't create anything.

 

The same happens if I go to an existing installation and try to edit it. The version drop-down is blank, despite the launcher knowing the version and being able to print it on the screen and launch the game. I just can't edit or create anything.

 

This has not bugged me too much because I use the Fabric Loader installer to create instances, but I would like to create a stock one at some point in the future.