This is due to a unit capacity conversion issue. Hardware manufacturers usually define 1K=1000 bytes according to decimal, while software providers (ex: Microsoft) define 1K=1024 bytes according to binary. In addition manufactures retain 3~5% of capacity for firmware, application software, and data storage maintenance. So there is the difference between actual capacity and marked capacity.
It is the problem of the FAT system. Most manufacturers formatted the USB disk in FAT file system. If you copy over 255 files to the USB disk at the same time, you can create a new folder or directly re-format the USB disk to FAT32 or exFAT. However, only the FAT format is compatible with most operating systems.
FAT 16 file formats can only support 2 GB size for a single file, and FAT32 file format can only support 4 GB size for a single file, so the NTFS or exFAT file format must be used instead for file sizes larger than 8 GB (including 8 GB). Please verify your file system format in advance.
The "Stream Loss" error message usually occurs as data is transferred from a storage device of NTFS format to a Flash drive of FAT or FAT32 format. Generally speaking, such"Stream Loss" message will not result in data damage or miss, so that you can continue without worry. This error message is generated due to automatic generation of "Thumbs.db" file in a folder because of NTFS format. Such error message will not occur by deleting "Thumbs.db" file before copying the folder.