I’m experiencing the same exact same thing, and I haven’t found a way to fix it either. My current workaround is to use Elixir Test - Visual Studio Marketplace
That way I get access to two new commands that I use regularly called “Run all tests on file” and “Run test at cursor”.
It’s not quite as nice as the VSCode test runner. You can’t debug a test using VSCode breakpoints for example. However, it works quite well to run the tests in the current file you’re working on for example, and then just use the (slow) VSCode test runner if you need to deep dive into why a specific test fails.
Thanks for the confirmation and the reference to the Elixir Test extension. Work around works fine for me. Just wanted to confirm I wasn’t missing something.