Piston doesn’t push blocks

Thank you for your report!
However, this issue is Incomplete.

Your report does not contain enough information. As such, we're unable to understand or reproduce the problem.

You are welcome to create a new ticket about your issue with more detailed information.
However, please review the Bug Tracker Guidelines and be sure to search for existing issues before writing a new bug report.

Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki

You can't push crying obsidian or nornal obsidian. It's basicly been that way as intended since they released the blocks.