Reproduction steps:
1. Open the attached “TestFixtureRiderIssue“ project
2. In the Project window, open the “Assets/Tests/TestScriptWithFixture” script using Rider IDE
3. In Rider, open Unit Test Explorer (Tests > Navigation > Focus Unit Test Explorer)
4. Run all tests

Expected result: All tests are successful
Actual result: “Tests/MyNamespace/TestScriptWithFixture” test was not run due to “The assembly for this test is not found…” error

Reproducible with: 3.0.24 (2021.3.30f1, 2022.3.10f1), 3.0.34 (2021.3.47f1, 2022.3.55f1, 6000.0.33f1, 6000.1.0a9)

Reproducible on: macOS Sequoia 15.1.1 (M1 Max), Windows 11
Not reproducible on: No other environments tested

Note: Tested on Rider 2024.1.6 (#RD-241.19072.26) and 2024.3.2 (#RD-243.22562.171)