The fastest way I know of to fix this, is to use the Rufus tool. Run it, accept the permission that allows Rufus to get updates, point to the USB drive in the Device box, then choose the "FreeDOS" option from the Boot selection. The default options are likely good for everyone, but for the 64 GB Samsung 3.1 USB drive I used, it chose MBR for Partition scheme, BIOS for Target system, Large FAT32 for File system, 32 kilobytes for Cluster size, Quick format checked, and the option of Create extended label and icon files checked.
When ready, click start on Rufus and after the format is complete, exit the tool. Now, open Windows File Explorer, right-click on the USB drive and choose Format, change the File system to NTFS or exFAT, the Allocation unit size to Default, type in W10 or W11 for the label, and select Quick format, then start. After it's complete, you can now paste mounted ISO files into the root of this USB drive, and Windows can boot into it.
If anyone knows of a more efficient method to achieve this, such as doing it all at once using command prompt and diskpart, or anything else that saves time, please let me know.