Roadmap Planner bars not displaying text on Firefox

Summary

Similar to this older report, when trying to view the Roadmap Planner macro on Firefox & MS Edge, the same will not provide options to see what's written in the bars.

Steps to Reproduce

1. Have Firefox running and create a new page
2. Once editing the new page, insert the Roadmap planner macro (through Insert/+ > Other Macros > Roadmap Planner)
3. Make sure to edit the bars and include some custom text
4. Publish the page

Environment

1. Firefox
2. MS Edge Version 18
3. Roadmap Planner macro

Expected Results

The text on the bars should be visible:

Actual Results

The bars are displayed without any text.

Workaround

Use Google Chrome.