While recently scouring the forums for something else I did notice a few posts that mentioned a preference for CBZ due to some issue with the CBR format(ting). One of the fixes mentioned was was repacking the CBR or repacking as CBZ. I've linked one of the discussions below:

https://ubooquity.userecho.com/topics/17-comics-sometimes-contain-a-thumbsdb-file-causing-an-error-with-the-folder-icon-and-online-reading/

Ugh sorry, I must've been in a private browsing session or cleared cookies. It's working normally so feel free to strike that comment.

On a similar note, is there a way to make the Read view default to "Fit to height" every time instead of "Fit to width"?

...unless this is already achievable via theme modification.

+1 to adding this feature. I wouldn't have thought it would require such heavy modifications however. I don't know enough about programming to know if looking at the code for the open-source Sumatra PDF Reader (which has the dual-page view feature) would help at all.