What would cause the Export Wizard to not display the fields on the left? If I click on a line, the Formula and Title of the field do display in the Column Properties section on the right, but not on the left.
I have no idea. I cannot duplicate this. What do you see if you click on the blueprint icon?
Well that looks ok as far as can be seen in that screen shot.
If you want to send me the database I can investigate further.
I am seeing the same issue. The “empty” lines in the Export Column Arrangement are holding their information but do not display it. I could get a “All Columns” template when I used the menu command Arrangement > Reset Arrangement… and then was able to edit the blueprint to choose the columns I want to export.
Ugg. I just tried it in Sequoia and I get the same results. So I guess this is a new macOS related problem. No need to send me the database Robert.
I am using Sonoma and the fields did later appear on a subsequent attempt.
And thank you to KJM as I hate to be the only one with issues. 
To clarify, I tried it on Sequoia and the fields were not shown, just like your screen shot. I do not have a computer with Sonoma installed.
Rober, it’s very interesting that the results are apparently intermittent. That might make this even more difficult to track down. We’ll see.
I found it to be intermittent which is never fun from a debugging standpoint. It did not work with several attempts, then it did work. Finding it works does not mean that it will work continuously unless the cause is found and eliminated.
I cheered too soon: macOS 15.3.2 was not the saviour. Got the empty column arrangement area some time later back again.
But I am able to get the dialog back to full display when I choose Export > Text (CSV)… first, cancel the Save dialog then and now choose Export > Custom Text Export…. Then all elements of the dialog are in place again.
If you compare Robert*s first screenshot with my screenshot, there are some differences (beside the invisible / missing elements of the column arragement area.) There is a much bigger gap between the (empty) column arrangement area and the column properties area.
So I am wondering if we are really seeing the same dialog here — or maybe a development version of this dialog instead of the complete(d) dialog.
There sure are some differences. I should have noticed that! Now we are getting somewhere. This is not a macOS problem. In fact, I have now duplicated the problem on macOS 11 Big Sur. However, frustratingly, it is very elusive. It works most times, but occasionally fails. I don’t see any pattern.
However, the arrangement is a big clue for me to follow. This is an elastic form, you can adjust the size of the form. Actually only the height can be adjusted, not the width. But I think what must be going on is that the elastic is somehow not calculating correctly when the form opens. This is messing up the size of the matrix object, causing it to not display anything. But for some reason this only happens occasionally, not every time. This is still going to be tricky since it doesn’t reliably duplicate, but should reduce the scope of the investigation. If all else fails I guess this could be made a fixed size window.
I do believe that I played with sizing the window, and many other try this, try that, kind of stuff to try to figure out why it was not working, so do not worry about the gaps. I caused those by resizing the window. And yes, the length of the record could be a part of it.
Actually, I don’t think you did. I saw the exact same gap on my computer when it failed, and no gap when it worked.