Trying to convert some jpeg files to pdf in Lightroom, but dropdown menu on File settings only gives me JPEG, PSD, TIFF, DNG AND Original?@
You can't covert to PDF in Lightroom's export window.
I believe you can do this in the slideshow module (but I have never tried).
I had a 'chat' with Adobe and they have advised to use the 'Book' module and effectively create a single page for a pdf file; not tried it myself yet either but the Adobe 'rep' did it on computer!
You can also use the Print module and print to a pdf.
Mac computers have had this option in the printer dialog for some time.
Windows I believe now has "Microsoft Print to PDF" as a 'printer' option.
Use a template or your own print layout then-
Set the Print module Print To: Printer. Then choose the "PDF" option in the 'printer' dialog.