Mysterious 'null' output in change detection part for no apparent reason

Dear CCDC team,

I was going about the change detection part algorithm by testing some points of interest when all of a sudden one point resulted in the output null for all output variables. I wasn't entirely sure about whether to post the issue here or whether to put it on Stack Exchange, so my apologies if this is off-topic.

The problem occurs for the coordinates of 80 deg longitude and 40 deg latitude, so somewhere in the Taklamakan Desert in NW China. I tried a bunch of points with the exact same input parameters, but I only had the error for this point in particular.

// Define the point that causes an error
var errorPoint = ee.Geometry.Point(80,40);

// First load the API file
var utils = require('users/parevalo_bu/gee-ccdc-tools:ccdcUtilities/api');

// Define parameters
// Change detection parameters
var changeDetection = {
  breakpointBands: ['GREEN','RED','NIR','SWIR1','SWIR2'],
  tmaskBands: ['GREEN','SWIR2'],
  minObservations: 6,
  chiSquareProbability: 0.99,
  minNumOfYearsScaler: 1.33,
  dateFormat: 1, // 1 = fractional years
  lambda: 20/10000,
  maxIterations: 25000
};

// Define input parameters for the CCDC main function.
var params = {
  start: '2000-01-01',
  end: '2020-01-01',
  ChangeDetection: changeDetection,
  StudyRegion: errorPoint
};

// Filter by date and a location
var filteredLandsat = utils.Inputs.getLandsat()
    .filterBounds(params.StudyRegion)
    .filterDate(params.start, params.end);
print(filteredLandsat);

The problem by now is not that there are not enough images available. print(filteredLandsat) yields ImageCollection 1006 elements).

// Attach the collection to the input paramters
params.ChangeDetection['collection'] = filteredLandsat;

// Run the CCDC algorithm
var results = ee.Algorithms.TemporalSegmentation.Ccdc(params.ChangeDetection);

// Reduce results to dictionary
var firstDictionary = results.reduceRegion({
  reducer: ee.Reducer.first(),
  geometry: ee.Geometry.Point(80,40),
  scale: 30,
  maxPixels: 1e9
});
print(firstDictionary);

// Reduce results to FeatureCollection
var outputByPoints = results.reduceRegions({
  collection: params.StudyRegion,
  reducer: ee.Reducer.first(),
  scale: 30
});
print(outputByPoints);

When I print the reduced output, it returns null for all 47 properties. I don't think the problem is with the reduction itself because when I try the script with another set of points it works fine. Like for instance with this feature collection:


ee.FeatureCollection([
  ee.Feature(ee.Geometry.Point(-60,-20), {'id': 0}),
  ee.Feature(ee.Geometry.Point(140,-20), {'id': 1}),
  ee.Feature(ee.Geometry.Point(-70,10), {'id': 2}),
  ee.Feature(ee.Geometry.Point(10,50), {'id': 3}),
  ee.Feature(ee.Geometry.Point(20, -10), {'id': 4})
])```

Something seems broken but I have no idea as to what it might be.

parevalo / gee-ccdc-tools

Mysterious 'null' output in change detection part for no apparent reason #2