Ver6 Beta5.
I've noticed this happening over the last couple of days.
I boot my PC up of a morning and start NBPro and hit the 'Update' button - all the groups update. I'm subscribed to 54 groups, some unsorted and some in GOG folders. I go through the downloaded headers and sort out what I want to download and download them. When it's finished all the headers get marked 'old' by hitting the delete button or permanently deleted with shift+delete.
When I do a new 'Update' by hitting the button a few hours later and watch in the 'Download' tab, all the groups appear and then disappear one by one but without any of the progress bars colouring up except for the last few which are some of the larger groups. When I then right click each group/GOG and click on 'show posts' - there are no new posts showing on some of the 'groups' individual tabs and I know that there should be new posts - this doesn't happen with all the groups/GOG. I can shut the group tab down and redo the show posts and sometimes extra headers will appear.
I then go to the 'Groups' tab and left click and hit 'download latest' for the individual groups/GOGs - the headers download and when I left click and hit 'show post' all the headers for the 'Display Age' limit appear - in this case 2 days - and not the new headers since the last update a few hours ago. I did have the Display Age set to 6 days and all the headers for 6 days used to appear again.
It doesn't happen with all the groups/GOGs but only with a few of them.