Large HTML Pages unable to save

[151SoGood]

I am using the extension via Firefox. I have a HTML page that is very long vertically (due to web page pagination; context: it is a forum community and I have loaded all the posts, which also has lots of images) - and whenever I try to save, it doesn't save.

On the 1st run, by right-click -> 'SingleFileZ' -> 'Save page with SingleFileZ' -> it prompted 'Deferred images' and 'iframe contents' at the bottom left. After 20 minutes of being 'stuck', I then clicked the Extension icon and I think this cancelled it. I ran it again via clicking the Extension icon, it gets stuck on 'Initializing SingleFileZ (2/2)' (message per hovering over Extension icon) when saving it on Firefox.

Any ideas how to troubleshoot or if SingleFileZ can handle the save?

NOTE: SavePageWE also has issues - it just is constantly stuck 'saving'. Only Firefox's 'Save As' feature works - but I don't want the separate HTML and images folder - I want it all as one single HTML file. Any ideas?