Comment 13 for bug 1195929

Well, as you seem to have some (waiting) time at you hands, maybe re-check you Inkscape version...

If you're really using 0.92.3 or later and the cancel button actually does *not* cancel the export for you, you're elcome to report a new issue (with a sample file and precise steps on how to reproduce) at https://inkscape.org/report.