The help page on Inserting External Data in Table (WebQuery) has this to say:
With the help of the Web Page Query (LibreOffice Calc) import filter, you can insert tables from HTML documents …
Your query is not returning a HTML table but rather a CSV file. Here is an example of a query returning a HTML table (taken from fdo#42377). When a web query returns with a HTML table you will see the Available tables/ranges area populated with HTML entries as shown in this example.
I would imagine this is why the dialog stops responding.
EDIT: One possible workaround is to dynamically link CSV data to a Writer document. Insert > Section… > Link section, check Link option and paste the URL into the File name field. Click Insert button. This gains you little other than getting the data into a document.
I worked out that if you remove the “cvs=true” part from the end of the link it returns XML instead of a CSV array. Unfortunately though it is still not a HTML table i.e., it lacks the surrounding <table> and other structural elements. Perhaps talk to the website developers and see if there is a parameter you can pass that will return a HTML table.
You could possibly script a solution (grab the XML, write it to a local file, run a sed/regex over it to convert it to a HTML table, link to resultant file) but this would require running the script to regrab/regex/write the data before opening the corresponding document each time.
