For what it's worth, I tested several books that worked with Kobo previously and no results today. I reverted back to calibre 5.11 and 5.12 and no results with either of those.
Spoiler:
Code:
calibre, version 5.13.0
ERROR: No matches found: <p>Failed to find any books that match your search. Try making the search <b>less specific</b>. For example, use only the author's last name and a single distinctive word from the title.<p>To see the full log, click "Show details".
Running identify query with parameters:
{'title': 'Red Thunder', 'authors': ['John Varley'], 'identifiers': {'isbn': '9781504063432', 'amazon': '0441011624', 'kobo': 'red-thunder-4'}, 'timeout': 30}
Using plugins: Kobo Books (1, 8, 0)
The log from individual plugins is below
****************************** Kobo Books (1, 8, 0) ******************************
Found 0 results
Downloading from Kobo Books took 1.936408519744873
identify - title: "Red Thunder" authors= "['John Varley']"
KoboBooks url: 'https://www.kobo.com/ebook/red-thunder-4'
parse_authors - author: "John Varley"
parse_authors - authors: "['John Varley']"
Could not find title/authors/KoboBooks id for 'https://www.kobo.com/ebook/red-thunder-4'
Kobo Books: 'red-thunder-4' Title: None Authors: ['John Varley']
********************************************************************************
The identify phase took 2.06 seconds
The longest time (1.936409) was taken by: Kobo Books
Merging results from different sources
We have 0 merged results, merging took: 0.00 seconds