Please note that if the name of the first poster does not match the name of the actual writer (say, for instance, the writer made the thread as an anon and then started using a name) then you must untick the 'Download OP Posts' checkbox for correct parsing.
I'm a fuckup, so what I meant in the last post is that you only need to manually uncheck the 'Download OP Posts' checkbox when the author started the thread with a name but just started using anon midway. There's already a contingency for the writer starting as an anon but then taking up a name mid-thread.
This is currently broken because apparently THP's story list HTML has changed or something. Working on a fix, you can still use it by searching for your desired fic, double-clicking it, manually copy-pasting the list of threads into the box, and then removing the commas before downloading.