Thanks for that.
We run a 56 to 72 page monthly magazine by printing 4 x A4 sheets on an A3 sheet of newsprint. (This is a free public-information magazine run by volunteers with costs covered by local advertisers and donations. We run to about 2000 copies per issue).
The Serif Pageplus imposition has worked extremely well for us. But we are aware that Pageplus is Legacy Software. Hence the planned transition to Affinity Publisher.
We currently use three RISO SF printers that take a PDF file as input but really are like fast photo-copying machines (only much heavier!). This means the file must be taken to them rather than printing directly a PC or MAC using any supplementary software.
My comment was not so much about the imposition process in Affinity Publisher (which seems to be adequate) , as the fact that Publisher cannot apparently produce a PDF file without losing that imposition.
Right at the end of the Affinity Publisher printer list is 'Adobe PDF' but it does not currently do anything. Exporting to PDF does, but the imposition is then lost.
So, for our purposes, Affinity Publisher 126.96.36.1991 is somewhat comparable with Scribus 1.5.3. in that we can only do the page imposition manually. We have tested all the Beta copies of Affinity Publisher and presumed that the saleable Publisher was now up and running. But, in effect, it seems that we have just made a donation for its further development. Fortunately, it is not particularly expensive.
We are also moving from Serif PhotoPlus to Affinity Photo for our graphic art and photo preparation but this has now been delayed because of cross-compatibility issues.
A meaningful time estimate for a functioning Publisher-imposited PDF file output would help. It is, of course, entirely possible that the procedure shown in the Tutorial has now been superseded with the recent upgrade to version 188.8.131.521. Certainly, the screen-images shown in the tutorial are not identical with the current reality.
Ah well! Life and software are full of challenges. 'Twere ever thus!