Summary

Custom fields formatting is not converted to markdown in the new Jira issue view.

Steps to Reproduce

1. Have a project with a text custom field using the Wiki Renderer;
2. Add some formatting in this field, using wiki markup;
3. Turn on the new Jira issue view.

Expected Results

The custom field should retain its formatting, similar to system fields.
Here's an example of two fields, Description and a Custom text field with the same formatting:

Actual Results

Only system fields are correctly formatted. Custom fields will be displayed with plain text:

Notes

Regardless if the custom field is using the Default Text Renderer or the Wiki Style Renderer, it's not possible to add any formatting in the field.

Workaround

Disable the Labs in the user profile in order to disable the new issue view (only for Software project):