phpbb2 to vB - no thumbnails in attachments
 

I have just migrated from phpbb2 to vB with impex but I am experiencing a problem with attachments.
Although all the attachments migrated OK I do not see theirs thumbnails in vB.
I have tried to Update Counters -> Rebuild Attachment Thumbnails but no luck.

I have tried to move all the attachments to file system and back to database but also no luck.

When I switch Thumbnail Creation off then I can see the attachments OK but they are big, I want to have them thumbailed.

Please help me.