How to hide the Adobe tool panel
When you open the PDF form filler window, the preview window on the right hand side should show you an image of the PDF form that you have selected. However you may find that the view is obstructed by Adobe's build in tools panel. This tools panel obstructs your view of the form you have selected. You will need to change a setting in Adobe to hide this panel by default.
1. Open a PDF in Adobe and in the menu bar go to Edit > Preferences
2. Go to the Documents preference
3. Untick 'Open tools pane for each document'
4. Click OK to save this preference
5. Important: You must now minimise the tool panel in the open document
It is important that you minimise the tool panel for this setting to take affect on all future pdfs that you open. To minimise the tool panel, click the little arrow and this will minimise the tools panel. If you ever need to reopen the tools panel you can just click the little arrow to make it reappear.
6. Form Filler view
The Form Filler window should now display a preview of the selected form correctly.