The problem is occurring because you have the Auto Numbers on pages instead of Master Pages. On a page it becomes the number and cannot update.
I made a master and applied it, you may want to name Sections and use the Section Field too for the Page headers.
Project Bug w Master.afpub
And for what is worth, I didn't get a crash. Possibly because I don't have the images (missing resources) so I deleted those and they may be the cause of the crash.
I'm full time on Linux and the ONLY reason I have a virtual machine running Windows is so I can use Adobe Creative Cloud.
We spend $1,500+/yr on CC and I would happily pay the same amount (or more) to the company who frees us from Adobe and Windows.
A lot of the comments on this thread are missing an obvious point - the reason designers aren't on Linux is because their software isn't on Linux. I bet there are a lot of people like me who have spent their entire career on Windows, hate Windows 10 and don't like the OSX ui/ux (a debate for a different thread).
Linux is easy these days with the introduction of Mint, and I would throw money at the company who would support Linux in a viable Adobe competitor.
Scottyb got a reaction from msdobrescu in Affinity products for Linux