If your image in Photoshop is "floating" above the plug-in, blocking the view, these instructions can resolve the issue:
Before you launch the plug-in, please disable the Floating Document (the floating window showing your image). You can do so by dragging the floating window to an anchor point so it is tabbed. After that, launch the plug-in and the problem should disappear.
You can also disable floating windows by selecting Window → Arrange → Consolidate All to Tabs.
Here are examples of a "floating" window in Photoshop and also an "anchored" window: