Trying to import from Thunderbird

Hi - I’ve just installed the free version of EMC to trial prior to purchasing the full version. It’s installed and offers me the option to import from Outlook or Thunderbird. I choose TB and then the programme seems to freeze - circling wheel, Task Manager say programme is not responding. It is using system resources, but I’ve left it for a couple of hours whilst I’ve been out and no change.

Something I should know? Or do differently?