End of Tape Message in iMovie locks up program

Using Imovie to convert 8mm tapes to hard drive and have done over 60 tapes successfully, but just got an end of tape pop up on my Mac saying the transfer went successfully and to close the popup & import screens, but when I click on the close or exit buttons, nothing happens as it has frozen the program and I have to force quit the program which loses the 1 hour import I did. I re-imported and got the same message and same result with the program frozen and not letting me exit those screens to then edit the import which I can see in the project section.