Can't open /dev/sda1 exclusively. Mounted filesystem?

I'm aware that there are a lot of similar questions about this, I have tried following through the responses but nothing has helped. I'm more than happy to post more logs if needed. The end goal: Have three ssds (sda, sdb, sdd) all mounted as 1 large folder but pvcreate is struggling with sda.

fdisk:

$ sudo fdisk -l
Disk /dev/nvme0n1: 465.78 GiB, 500107862016 bytes, 976773168 sectors
Disk model: Samsung SSD 970 EVO 500GB               
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: 46B511CA-4396-4D74-8774-ACB5C967DFE7

Device             Start       End   Sectors   Size Type
/dev/nvme0n1p1      4096   1023998   1019903   498M EFI System
/dev/nvme0n1p2   1024000   9412606   8388607     4G Microsoft basic data
/dev/nvme0n1p3   9412608 968380462 958967855 457.3G Linux filesystem
/dev/nvme0n1p4 968380464 976769070   8388607     4G Linux swap


Disk /dev/sda: 476.96 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: Samsung SSD 850 
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: dos
Disk identifier: 0x000cc98b

Device     Boot Start        End    Sectors  Size Id Type
/dev/sda1        2048 1000215215 1000213168  477G 8e Linux LVM


Disk /dev/sdb: 476.96 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: Samsung SSD 850 
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: dos
Disk identifier: 0x4bfa6fac

Device     Boot Start        End    Sectors  Size Id Type
/dev/sdb1        2048 1000215215 1000213168  477G 8e Linux LVM


Disk /dev/sdc: 6.25 GiB, 6702455296 bytes, 13090733 sectors
Disk model: Internal Storage
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: dos
Disk identifier: 0x00000000


Disk /dev/sdd: 476.96 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: Samsung SSD 850 
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: dos
Disk identifier: 0x394a7ef1

Device     Boot Start        End    Sectors  Size Id Type
/dev/sdd1        2048 1000215215 1000213168  477G 8e Linux LVM


Disk /dev/md126: 476.45 GiB, 511570870272 bytes, 999161856 sectors
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: dos
Disk identifier: 0x000cc98b

Device       Boot Start        End    Sectors  Size Id Type
/dev/md126p1       2048 1000215215 1000213168  477G 8e Linux LVM


Disk /dev/mapper/cryptdata: 457.26 GiB, 490974764544 bytes, 958935087 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/data-root: 457.26 GiB, 490972643328 bytes, 958930944 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/cryptswap: 3.102 GiB, 4294442496 bytes, 8387583 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

pvcreate:

$ sudo pvcreate /dev/sda1 /dev/sdb1 /dev/sdd1
  Can't open /dev/sda1 exclusively.  Mounted filesystem?
  Can't open /dev/sda1 exclusively.  Mounted filesystem?

No clues in dmsetup

 sudo dmsetup ls
cryptdata   (253:0)
data-root   (253:1)
cryptswap   (253:2)

I've recreated the partition with fdisk -c /dev/sda setting the type to LVM (e8).

A different questions suggested overwriting the beginning of the partition with dd if=/dev/zero of=/dev/sda1 bs=1M count=20

I have also checked the LVM configs at /etc/lvm/lvm.conf and there are no filters in place.

Sorry for not providing enough detail at the start!