GrapheneOS-Jub Thanks & sorry noob with wormhole. Here's from Streamable. 1st time upload to that site. Hope this streams.
https://streamable.com/o2t3pb
Sorry for the delayed response, it was night where I live.
Thank you for the link!
It looks to me like the finalizing process; usually when a file is done copying, it may stay at 100% for a while in order to finalize the copying process, depending on the speed of the external device, it may take a very long time to finish. It is not advisable to remove the USB device before it is completely finished.
Give it a few minutes, up to an hour, perhaps the notification will go away eventually?
Overall I can see nothing wrong with it, when I transfer a very large file on a slow USB drive, it usually gets "stuck" at 100% for a long period of time (it is not actually stuck) while the process is finalizing. Eventually I can eject the drive when the message disappears and the process is finished. (Always press the eject button in the software, never just pull it out, which may corrupt the external drive)
Furthermore, it is important to put the phone at a stable place like a table when connecting to an external drive, USB ports have the tendancy to disconnect when you juggle the drive or cable around.
However, when people are transfering a small file, (like a photo or the files you tried to copy) it should not take very long unless the USB drive is corrupted or something else is going on. Corruption can express in several ways, including files turning into different weird filenames like 29E4%#29.txt for example. (Unless it is an encrypted file)
Usually you can press on the "100%" notification to expand it to see what it's doing.