There are 3 steps:
1) Get the right (full?) format file.
2) Alf it unless that magazine is sensible like TOR is with books.
3) Side-load it back on a device with reader software that will view it right.
For BN - perhaps like Amazon they send different formats to different devices, or maybe Nook for PC is just that old and buggy. Files from it are just cover, text, and a few small thumbnails. As I recall, NG magazine never displayed right in Nook for PC or at least not since I started the subscription in 2012. Files from my NC, however, do display correctly. I would bet the Nook Tablet would work too. I don't recall if the HD/HD+ line has accessible files. The Sammie Nooks (and Nook Apps) do not. Does your NST display the magazine right (except in B&W)? If so, you may be able to use the file from it. (If I remember correctly that NST has accessible files.) Try a file from the NST. If not, pick up a working NC or NT on ebay etc. If it needs a new battery, see
www.newpower99.com or similar.
I use Calibre with the tools to manage my library including NG magazine. (Pest Control, editing metadata, adding tags etc. so I can find things, then side-loading to my device for reading). The Calibre viewer will display the same cover/text/no photos whether the file is abridged (as from Nook for PC) or unabridged (from NC).
I use Calibre Companion to manage the library on device (shelves/collections/tags and sorting). If the magazine file side-loaded was from an abridged source, you'll see the same cover/text/no photos version you saw in the Calibre viewer. If the side-loaded file was from an unabridged source, you MAY see some lovely photos depending on the reader software.
I use the Nook App to read things on my SGT2S-8 and previously my SGT4N-7. I like it better than other reader software programs I have tried. I discovered this week the plain Nook App in Google Play did not correctly display magazine files I knew were OK from SGT4N-7 side-loading experience. After some chatter on the BN forum mentioned a special Kindle for Samsung App, I went looking for a Nook for Samsung ...found Nook for Galaxy Tab 4 in Google Play that was posted or maybe updated the day before. Back in business! It works on a Samsung Galaxy Tab S2-8 also. Maybe other people with different tablets could see if it will work on their tablets. Or suggest other reader Apps that do a good job with photos or comics (there's a reference to something comic in the settings).
Two potential flies in my honey :
1) if/when my NC dies, so does my subscription since I will likely not be able to future-proof any more.
2) My subscription may die anyway if I can't find any other software to read it with. Is Nook reader (for Samsung) really the only one? I can't imagine this is true. The value of epub is it can be converted if (when) formats evolve and reader software expects something new. If (when?) Nook for Galaxy Tab is orphaned and falls behind Android or whatever system software is in vogue at the time...is the format legible to anything else? Something tells Nook for Galaxy Tab 4 App to use Article View (and a lovely view it is). What? Is there another reader App that can also view this file correctly? Without understanding why it is working now, I am not confident of finding another device / reader software combo that can also read it in the future.