files.list behavior seems to have changed - google-drive-api

Question

I've been naming Drive files with a very specific convention to facilitate searching for them from an app. The search functionality in the v3 Drive API (files.list) had been working as recently as three weeks ago and has since stopped working.
For example, using the following files,
"ABC-123 template", "ABC-123 gogo", "ABC-123 bobo"
... enables me to search via the API with
name contains 'ABC-123'
This search should return all three files. Instead it returns no results. Note that the same query in the Drive web interface is successful and the convention follows the rules laid out in the documentation.
This was working, and now it has stopped. Did the search API change?! I can find other files with the implementation, just not those that use the naming convention.
Here's the full code snippet of the request in NodeJS.
Google.prototype.findFiles = function(file_prefix, callback) {
var service = google.drive('v3');
service.files.list({
q: "name contains '" + file_prefix + "'",
fields: 'nextPageToken, files(id, name)',
spaces: 'drive',
corpus: 'domain',
auth: this.auth
}, function(err, response) {
if(err) {
console.log('Error : findFiles failed. ' + err);
callback(err);
} else {
callback(null,response.files);
}
});
};

Answer 1

The root cause turned out to be the corpus value. For reasons that are not clear from the documentation, the use of corpus=domain is preventing the search from working.
Removing corpus: 'domain', from the above code sample solves the problem.
The files I'm searching are very much in my domain. I'm not sure if this behavior changed recently or if added this constraint in the code and simply don't remember doing so.
Onward.