Can't Open Existing Luks File on New Computer Using Cryptsetup

I have an encrypted partition called keys.img that I have used for years. Here's how I've always decrypted and mounted it:

sudo cryptsetup open --type luks mykeys.img mykeys
sudo mount /dev/mapper/mykeys /mnt/mykeys 

I recently restored a backup of this file to a new computer running KDE Neon (which is based on Ubuntu 20.04). When I try the same commands on the new computer I get the following error:

• No key available with this passphrase

The funny thing is, I'm able to decrypt the exact same file on a Debian server running version 10. So I think I'm missing something with the newer OS or kernel.

Here's what I've tried:

1. Passwords: I'm not typing the password in either case, I'm copying and pasting it in. That leads me to believe that it's not a password issue.
2. Checksum: Both copies of the mykeys.img file have the exact same md5sum hash
3. Reboots: I've done that a few times
4. initramfs: I saw a few posts stating that this should be regenerated. I therefore ran sudo update-initramfs -u and got this output:

W: Possible missing firmware /lib/firmware/i915/skl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/bxt_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/glk_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/kbl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/cml_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/icl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/ehl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.5.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_huc_7.5.0.bin for module i915
W: Possible missing firmware /lib/firmware/i915/tgl_guc_49.0.1.bin for module i915
W: Possible missing firmware /lib/firmware/i915/dg1_dmc_ver2_02.bin for module i915

I then rebooted and nothing changed.

Does anyone see what I might be missing?

Here's the debug output when I try to open the mykeys.img file btw:

# cryptsetup 2.2.2 processing "cryptsetup open --debug --type luks /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img mykeys"
# Running command open.
# Locking memory.
# Installing SIGINT/SIGTERM handler.
# Unblocking interruption on signal.
# Allocating context for crypt device /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img.
# Trying to open and read device /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img with direct-io.
# Initialising device-mapper backend library.
# Trying to load any crypt type from device /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img.
# Crypto backend (OpenSSL 1.1.1f  31 Mar 2020) initialized in cryptsetup library version 2.2.2.
# Detected kernel Linux 5.11.0-41-generic x86_64.
# PBKDF pbkdf2-sha256, time_ms 2000 (iterations 0).
# Reading LUKS header of size 1024 from device /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img
# Key length 32, device size 24576 sectors, header size 2050 sectors.
# Activating volume mykeys.img using token -1.
# Interactive passphrase entry requested.
Enter passphrase for /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img: 
# Activating volume keys4s3.img [keyslot -1] using passphrase.
# dm version   [ opencount flush ]   [16384] (*1)
# dm versions   [ opencount flush ]   [16384] (*1)
# Detected dm-ioctl version 4.43.0.
# Device-mapper backend running with UDEV support enabled.
# dm status keys4s3.img  [ opencount noflush ]   [16384] (*1)
# Trying to open key slot 0 [ACTIVE_LAST].
# Reading key slot 0 area.
# Using userspace crypto wrapper to access keyslot area.
# Reusing open ro fd on device /home/tom/Pam-Syncthing-Root/vault/images/mykeys.img
# Trying to open key slot 1 [INACTIVE].
# Trying to open key slot 2 [INACTIVE].
# Trying to open key slot 3 [INACTIVE].
# Trying to open key slot 4 [INACTIVE].
# Trying to open key slot 5 [INACTIVE].
# Trying to open key slot 6 [INACTIVE].
# Trying to open key slot 7 [INACTIVE].
No key available with this passphrase. 
# Interactive passphrase entry requested.