After all, for one of my books it worked by sending a .mobi conversion to my Kindle email (.docx didn't work, also tried .txt but I think Kindle doesn't support that). Today will try the other one that I know is failing.
The initial conversions were all done with Calibre - it's the only tool I use. Though the .mobi I sent myself was done with some other tool (sorry, forget which one, tried a few). Today I'll try the other one that I know is failing.
If you want to check, just for curiosity's sake, I can send you the files privately. But thanks for trying to help, much appreciated
