I am unable to copy a certain file. At first I tried using a cloud share app, then USB file transfer, then ADB, then local file browsing apps, finally a terminal emulator. All fail. I can see the file and the app that created it can partially interact with it, but I cannot copy the file, permission denied. Phone is rooted. This is a large file created by TitaniumBackup. It's large because the backed up app has a lot of data, about 4 GB worth. I can copy all the small files that Titanium creates during its backup process, including the apk and properties files. And I can rename the big file, even delete it, just not copy. Even Titanium itself can delete and restore backups but not upload to the cloud using the built-in function to Sync to Google Drive. I am thoroughly confused.
I don't think it matters but this is a rooted Pixel 5 with stock ROM.
-EDIT- responding to alecxs
adb: error: failed to copy '/sdcard/TitaniumBackup/ws.clockthevault-20201202-212154.tar.gz' to 'vaultcopy.gz': remote open failed: Permission denied ls -lZ -rw------- 1 media_rw media_rw u:object_r:fuse:s0 Before chmod: -rw------- 1 u0_a256 After chmod: -rwxrwxrwx 1 u0_a256 But pull still fails: adb pull /data/media/0/TitaniumBackup/ws.clockthevault-20201130-045341.tar.gz vaultcopy.tar.gz adb: error: failed to stat remote object '/data/media/0/TitaniumBackup/ws.clockthevault-20201130-045341.tar.gz': Permission denied