[andhistablet]

Hi all. I have a large amount of ebooks in Calibre (over 10,000) and I have tried moving a large chunk of them to my Kindle Oasis. When I attempt to transfer as one job, the program crashes, and several popups have mentioned a memory error. If I try to do a large batch (1,000 for example), the Kindle crashes Calibre when trying to reconnect and read Kindle metadata. When "Getting Books from Device," Calibre crashes and closes at around the 90% mark.

As a result, I move my books in batches of ~100 and it seems to work okay. However, once on the device, not all of them have covers. I am well aware of the cover bug and the need to disconnect/reconnect to Calibre to restore lost covers, but my issue is that they never transfer in the first place and definitely not restored on a reconnect. If I am doing only one book at a time, there is no issue, but the batches of 100 largely do not show covers, while some of them do. My questions:

1. Is there a list of parameters or signs as to why certain books would or would not show covers? Perhaps a published list of best "practices?" Or maybe a limit of book transfers per job?

2. Obviously I have a large number of books on my device. Is there any way to send cover metadata to the device again barring a removal + new transfer of ALL my files?

3. Any options I may not have tried?

Any thoughts are welcome as I am out of ideas and have even reset my kindle to factory settings once while trying to find solutions. Running Calibre 5.42. Thank you in advance!