The Compose box should look precisely like the above.
You have tested the program on two PCs with two Videopad releases ... and had the same results.
It's assumed that you have also tried several different files in building the project?
It makes no sense that export is inconsistent.
When composing your next response note the Choose Files link (to the right of the paper clip) at the bottom of the compose window.
Click it and attach your files, if they aren't too large. No Personal Message necessary.
It's possible that the attachment feature isn't available to non-administrators via the compose window, but it surely is via a Personal Message.
Have received many in the past. Beyond that, out of ideas, sorry to say...