Great I also tried your solution - opening the file in acrobat first and then selecting "edit form in designer" from the Form menu and it also worked for me. Seems like two relatively easy fixes. Hope they work for others as well

My preview pdf tab is sometimes there and sometimes not. I found that if it is not there the following gets it back.I save the form and then do File>distribute form. When the wizard comes up I just cancel it. This opens Acrobat and displays the form, which I can then close. When I go back to designe...