The vxfenswap utility deletes comment lines from the /etc/vxfemode file, if you run the utility with hacli option (3318449)

The vxfenswap utility uses RSH, SSH, or hacli protocol to communicate with peer nodes in the cluster. When you use vxfenswap to replace coordination disk(s) in disk-based fencing, vxfenswap copies /etc/vxfenmode (local node) to /etc/vxfenmode (remote node).

With the hacli option, the utility removes the comment lines from the remote /etc/vxfenmode file, but, it retains comments in the local /etc/vxfenmode file.

Workaround : Copy the comments manually from local /etc/vxfenmode to remote nodes.