I'm having this problem with Lacerte 2020. I have 256 partners with about 200 tagged for export. It's a BIG file. I did a cold reboot and went into diagnostics too make sure everything was still good and then exported. I got the "No K-1 data..." message. I exited to the client list screen and tried again and it worked. I wish I could pick and choose which K-1s to re-export when needed without having to tag and untag 200 partners.