This is an SMB that works with other apps like VLC.The iPad Pros I use with Panels usually have problems like this.The cbr files in the folder aren’t corrupt but when I got to import from files and select all or select more than a few I am an unable to comics.The only sure way to be able to add is to select and import one by one. I have a video to show what happens.
We’ll look into it. SMB is quite finicky, but maybe there’s something we can do.
Feel free to send us that video, 
any additional information might help narrowing the issue down.