Attaching images in the issue view does not always bring up the attachments modal

Summary

When attaching an image via copy pasting into the comment box on the issue view, sometimes the "Attach Screenshot" modal fails to appear, and instead the image is automatically uploaded. We have not been able to narrow down why this occurs, and it occurs randomly.

Why this is a problem

The user loses the ability to double-check this is the image they want to upload, and to choose the image name.

Steps to Reproduce

1. View an issue, either from queues or /browse
2. Paste in an image into the comment box using CMD+V or Ctrl+V
3. The "Attach Screenshot" modal may fail to display, and instead the image is uploaded straight away.

Expected Results

The modal should always display before uploading the image.