@allybeedesign, First, please confirm you are using Firefly Beta's Generative Fill module with an image you have uploaded yourself. Next, have you tried closing out and clearing your cache and/or switching to a different browser? Or is it that you aren't using the module in the right way to remove a power line? Are you using the remove tool first and brushing away the power line, then clicking the Remove button? With this module, you don't need to use a text prompt to remove an item.
Here is an example I just made to show how to use the Remove tool:
The dialogue box appears when you want to insert something, after you first select the Insert tool and brush in the area you want to fill. Use the dialogue box to write what you want to add to that space. I hope this is helpful, and let us know if it's some other problem you are experiencing with Firefly Beta's Generative Fill!