There was a change for the default functionality for the [mashup] shortcode. Rather than showing all maps, it only shows the ones on the current page by default, to prevent accidentally running long queries.
You can’t use mapid for the mashup but you can specify a specific post using the ‘p=’ parameter. There should be an example of a mashup like that in the documentation.
There’s no overall list of maps yet, but it will be coming in the next version.
If you look at the front of this forum, there’s a ‘sticky’ FAQ posts that describes how to add missing translatins.