What i can tell from your screenshot is that your pop-up display the image entity with some values that belong to this entity.
If you want to show some values from the workout entity as well you can do this in a couple of ways:
I have created the following solution:
When user wants to add a new workout inventory item, he goes into the Workout inventory items page
Clicks on the ADD button that triggers a microflow that will create the object and open the page below
The user presses check mark to include images related to the workout item.
Which will invoke a nanoflow which will in turn trigger the images page