Single letter on a page - won't output
I wanted to PDF a series of single letters on SRA3 pages. Simple and easy...
New document, SRA3 portrait.
Draw a text box, corner to corner, to fill the page.
Type a single capital 'H' in Helvetica. Centred, then centred vertically (Cap+Accent).
Enlarge the letter to 960pt to be 'big' within the area.
Export to PDF.
This gives an error message "Unable to create the "Users/.........pdf file"
I get the same error if trying to output a single letter at whatever size! I've tried 4pt to 500pt.
Now, if I add another letter (even one that's only, say, 4pt) it will output!
Why can't I PDF a single letter??
What the dickens is going on?