OK, I've done a bit more digging. I thought it might be the full stops in the filenames that caused the problem, but removing them did not help. Checked some other directories and got very inconsistent results. I've a bunch of directories of home videos, by year, and then nice clean file names with a numerical prefix, like "02 Zoo Trip.mpg". In the same filepath view, some directories show up nicely in filename sequence, other don't. Some have a nice sequence break 07-21, and then 01-06, others are more random.
And then I notice that some complete sub-directories are missing. I try to add the individual folders, but the root directory is already there. No exclusions, no ignore previously deleted.
I'm starting to wonder if I should be re-building my whole database....
EDIT, so I gave that a try, and the missing directory problem has gone, but the strange sequence issue still remains. A bit more digging identified that the file are in date created sequence.
So, how do I get the a filepath view to show me files in filename sequence? I've tried changing the Settings on the filepath to Name, but that doesn't seem to have any effect?