PHPUnit does not load some of the tests

I have a test folder in one of my modules with three subfolders:

Model
Helper
Integration

works

phpunit --group My_Module 

runs only tests in the Model and Helper directories, and the Integration folder remains untouched. Test files are located directly in the folder in all cases, so I'm not sure what causes the problem. Here is my phpunit.xml:

<?xml version="1.0"?>
<!-- initial phpunit configuration file, that you can modify for your project needs -->
<phpunit cacheTokens="true"
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         stopOnError="false"
         stopOnFailure="false"
         stopOnIncomplete="false"
         stopOnSkipped="false"
         strict="false"
         verbose="false"
         bootstrap="app/code/community/EcomDev/PHPUnit/bootstrap.php">
    <listeners>
        <listener file="app/code/community/EcomDev/PHPUnit/Test/Listener.php" class="EcomDev_PHPUnit_Test_Listener" />
    </listeners>
    <testsuites>
        <testsuite name="MyApp">
            <directory suffix=".php">app/code/local/*/*/Test/*/</directory>
        </testsuite>
        <testsuite name="Magento Test Suite">
            <file>app/code/community/EcomDev/PHPUnit/Test/Suite.php</file>
        </testsuite>
    </testsuites>
    <filter>
        <blacklist>
            <!-- Exclude Magento Core files from code coverage -->
            <directory suffix=".php">app/code/core</directory>
            <!-- Exclude EcomDev_PHPUnit classes from code coverage -->
            <directory suffix=".php">app/code/community/EcomDev/PHPUnit</directory>
            <directory suffix=".php">lib/EcomDev/Utils</directory>
            <directory suffix=".php">lib/EcomDev/PHPUnit</directory>
            <directory suffix=".php">lib/Spyc</directory>
            <directory suffix=".php">lib/vfsStream</directory>
            <!-- Exclude Mage.php file from code coverage -->
            <file>app/Mage.php</file>
            <!-- Exclude template files -->
            <directory suffix=".phtml">app/design</directory>
            <!-- Exclude Varien & Zend libraries -->
            <directory suffix=".php">lib/Varien</directory>
            <directory suffix=".php">lib/Zend</directory>
        </blacklist>
    </filter>
    <logging>
        <!-- Uncomment this line if you want to have coverage report generated every test run
        <log type="coverage-html" target="var/phpunit/coverage" charset="UTF-8"
              yui="true" highlight="false"
              lowUpperBound="35" highLowerBound="70"/>
        <log type="coverage-clover" target="var/phpunit/coverage.xml"/>
        -->
        <log type="junit" target="../build/logs/junit.xml" logIncompleteSkipped="false"/>
    </logging>
</phpunit>

The version of PHPunit that I run on ubuntu VM on is 3.7.28. How can I run all the tests? Help would be greatly appreciated.