on a mac "preview" opens the pdf with no issue.
not so the adobe acrobat reader...
it looks like, scribus is doing something that adobe does not like... or the malicious would say that adobe is doing it on purpose :-)
i had some doubts... about the images being the culprit...
i've created a new document and pasted there you're first page, then multiplied it 6 times...
preview has some issues displaying the pdf... but it somehow works...
adobe: nah.
i then created a pdf without the first and last pages (you can pick the 2-91 range when exporting): oh wonder, it opens instantly in adobe reader!
next try: ungroup the first page, send the car to the patterns, delete all the page content, insert the care from the patter and multiple duplicate it. copy paste the first page to the last page.
ok, in preview, but still no chance in adobe. (well, this time i could see the first page, but it still was unusable.)
last try: remove all shapes from the first and last pages, insert a full page rectangle, set its background color as a pattern and choose the car you previsously have put in the patterns.
bingo: shows instantly in adobe acrobat reader!
so, i guess that what we could ask scribus to do, is to check what is the difference between duplicating a pattern or using a pattern as a filler...