Initiative and Dance Bard's Agile Strikes

I am looking for clarity on something regarding a College of Dance Bard and the use of Bardic Inspiration for an Agile Strikes with Tandem Footwork. 

Tandem Footwork allows the use of a Inspiration Die when rolling initiative. Agile Strikes allows an Unarmed Strike when a Bardic Die is expended as part of an action, bonus action, or reaction. I get the argument that a D20 test is not an action, however there are no actions I can see that the Bardic Die would be expended in that case. Additionally, under the Actions tab of a Dance Bard is where Tandem Footwork is listed, indicating that  D&D Beyond is considering it a part of an action at least. Am I missing an action where it could be used?

This may have been discussed in another thread, but I did not see one on my search and I am wondering how others have handled it at the table. Whether it is RAW is another aspect people could argue about.

Rolling Initiative is not an Action, Bonus Action, or Reaction, so you can't use Agile Strikes to make an Unarmed Strike with it.

There are two main times when you can use Agile Strikes:

• When you give someone Bardic Inspiration using the base Bard class feature (this uses a bonus action, so it qualifies)
• When you use the level 6 feature Inspiring Movement (this uses a reaction, so it qualifies)

The feature is left somewhat open-ended and not explicitly limited to these two things so that it can apply to potential future abilities granted by things like Bard-specific feats and magic items.