Export problem

I had hoped that this screenshot would give me more information about those images. Unfortunately it does not even show their names, so I can't even see which ones do export and which ones don't... I also can't see how large the images are, but they do look like large images. Lightroom Classic has certain limits for image sizes and I noticed that you have set the JPEG quality in the export dialog to 100. That will create very large images and is useless. You won't see any difference compared to setting it to 90 or even 80. So maybe you should try that and see if it solves it. That is the last thing I can think about. If that does not solve it, then I'm out of ideas.