OK, here we go...
Yes, my font names are case sensitive and perfectly correct according to that instruction. And yes, I know you need to rename the books to .kepub.epub. I use calibre to convert the books and then open the containing folder and copy the files onto the device with the correct extensions. This has always worked. This is the only book that hasn't and still doesn't work manually coping to the device.
I used to send to the device via the kobo utility, but that function broke some time ago. I tried it tonight and yes, it does send books to the device. So I assume that was resolved in a recent update. I apologize for not testing that part further. I had recently had the issue and assumed nothing had changed in the short time between now and then. Apparently I was wrong.
The database error however, was not the firmware issue, it was saying the database couldn't be found. It wasn't obvious, but I checked windows, and the path to the database file didn't exist. I created the directory in windows manually, and reconnected the kobo, and it appears to have solved the database error as all the functions work and no errors.
FYI my version are as follows:
My reader is 4.26.16704 (0af09acc53, 2/10/21)
Calibre is 5.12.0
Kobo Utilities v2.12.3
I believe I found the issue with the fonts as well. Thank you Sirtel for the link
https://wiki.mobileread.com/wiki/Kob...play_Correctly
It was not an issue of epub formatting, name of fonts, or any of that. Apparently, as per that article you can only have the 4
primary variants of a font (regular, italic, bold, bold italic). I have never seen that specifically written anywhere, so never thought to restrict a font to only those (how would I know a book wouldn't contain other weight variants :-P hehe). The Alegreya and multiple other fonts all had other variants. I simply deleted all the variants except the main four and loaded an epub and the font immediately looked correct.
It also fixed the line-height issue. I assume it was loading the font variant and the font somehow changed the spacing either through the font properties or the fact that it couldn't understand the abnormal font variant. I'm not sure. But set at the lowest setting, the line height was roughly 1.5 as someone mentioned earlier and jumped up quickly with each setting step. But without changing the ebook styles at all, simply fixing the font issue now shows expected minimum and maximum line height adjustments.
So thanks for all the help and patience. It's been hard not being home a lot with access to do more testing. :-o But it feels great knowing i can have my fonts now. Bitter is amazing. You should give it a good while reading with it.
