During July 2025, Ortner focused on improving the reliability and correctness of the RaGroupby function in the apache/systemds repository. He addressed a runtime error that occurred when groups had varying row counts by implementing a matrix padding strategy, ensuring the permutation-matrix could handle heterogeneous group structures without exceptions. Ortner reinforced this fix by adding targeted tests to prevent regression and validate the solution across diverse datasets. His work leveraged skills in algorithm implementation, data engineering, and testing, using Java and DML to enhance the robustness of data processing workflows. The changes contributed to more stable production data pipelines.