Bugfix/symbol sub doesn't preserve opgroup

[yao-cqc]

Description

Please summarise the changes.

Related issues

Fixes #1615

Checklist

• [x] I have performed a self-review of my code.
• [ ] I have commented hard-to-understand parts of my code.
• [ ] I have made corresponding changes to the public API documentation.
• [x] I have added tests that prove my fix is effective or that my feature works.
• [x] I have updated the changelog with any user-facing changes.