Markus Brandstetter schrieb:
Export always used to work and still works fine with earlier versions of the same document. Between these versions I did not add anything new I hadn't added before, except for one footnote. The preamble of the not-working version contains one paragraph of "textclass specific commands" that the older version does not have.
This command is added by LyX for a LyX-specific list environment. But a list within a footnote is quite unusual and might be the problem. So I would check that the footnote and its content are in the Standard environment and not set to be a list, section or whatever.
Btw.:
User specified LaTeX commands. \usepackage[TS1,T1]{fontenc} \usepackage{textcomp}
You don't need these commands, LyX takes care of them automatically. (As you can see in your posted code, LyX added these packages already.)
\usepackage{ae}
This is also not needed, you can select the AE fonts via the LyX document settings. regards Uwe