Encrypting

Same problem by using the disc utility.app. Encryption does not show up when following as per apple support instructions...have tried already with different USB sticks.

My Mac is up to date with MacOS Big Sur

You have to select GUID Partition Map to erase the drive.

To get that option, you have to select Show All Devices from the View popup menu.

You will have to erase the drive to encrypt it since it is not already GUID Partition Map. If you have data on the drive, move it someplace else before erasing the drive.

As per Source of below >>> https://support.apple.com/en-ca/guide/mac-help/mh40593/mac

Protect your Mac information with encryption

Using removable media, such as CDs, DVDs, removable disks, or memory cards, has become a popular way to transport information. However, if the removable media is lost or stolen, someone else can access its data by mounting the media on another computer.

If you want to keep private or confidential information secure on removable media, you need to encrypt the information on it.

WARNING: When you encrypt a disk or other media, the disk format is converted to the APFS format and then encrypted. Macs with older versions of macOS that don’t support the APFS format are not able to read the device’s data. Consider whether you need to connect the media to a Mac with an older version of macOS before you encrypt the data. You can also update your other Mac to the latest version of the macOS that supports the APFS format.

What file format is the USB Stick Drive ??

Is it HFS Journaled with GUID Partition Map ??

Is it Fat32 with MBR or exFat also with MBR ??