Heredoc not working in bash script

I made a bash script that was working in Ubuntu mate but now it won't work in Manjaro. It fails on this method:

#!/bin/bash

dev_block="/dev/sdb"

createPartitions(){
    
        echo "Creating Partitions on "$dev_block"..."
        sfdisk $dev_block -uS <<-EOF
        start=63, size=409600, type=c, bootable
        start=411648, type=af
        EOF
    }

createPartitions

I get this output...

Creating Partitions on /dev/sdb...
Checking that no-one is using this disk right now ... OK

Disk /dev/sdb: 28.84 GiB, 30966546432 bytes, 60481536 sectors
Disk model: USB FLASH DRIVE 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: EB88C926-F304-6D45-82C8-0BAC5E73A2CB

Old situation:

Device      Start      End  Sectors  Size Type
/dev/sdb1    2048   411585   409538  200M EFI System
/dev/sdb2  413633 60481502 60067870 28.6G Apple HFS/HFS+

>>> Created a new GPT disklabel (GUID: 0EBA642D-3CB5-8841-A150-D18AC387D65F).
/dev/sdb1: Failed to add #1 partition: Invalid argument
Leaving.

I also tried moving the EOF back so there is no tab before it.

createPartitions(){

    echo "Creating Partitions on "$dev_block"..."
    sfdisk $dev_block -uS <<-EOF
    start=63, size=409600, type=c, bootable
    start=411648, type=af
EOF
}

I checked and there is no tab or whitespace AFTER the closing EOF. But also in Ubuntu I didn't have to move that closing EOF back.

How do I debug this? Maybe sfdisk behaves differently in Arch?

Cheers.