On my iPad Pro with iPadOS (13.0, 17A5534f) it is not possible to put data from an external device to my iPad Pro storage. Every time I try to copy paste jpgs or raw picutes no matter what, an error acures: "The process can not be completed. Communication with the help app is not possible." All the youtube guys put there sonyalpha cams, sd card readers or even their dji mavic 2 pros directly into the iPad and it works. I tryed to format my cd card to fat32, ntfs and exfat, no change. Please help:)
iPad Pro, iPadOS data management doesn't work
In the past, the ability to communicate with a card reader has gone away during betas, at least with iOS 10, 11 and 12, so it's not surprising to see history repeat itself. Might need to wait until later in the beta cycle, or for iOS 13 release version.