Ok, aside from uboot, lets see if we can find a difference in our set up. Can you try:
fdisk -l:
$this->bbcode_second_pass_code('', 'sudo fdisk -l /dev/mmcblk0
[sudo] password for summers:
Disk /dev/mmcblk0: 29.83 GiB, 32010928128 bytes, 62521344 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: 0x57f70b45
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 2048 62521343 62519296 29.8G 83 Linux
')
tune2fs -l
$this->bbcode_second_pass_code('', 'sudo tune2fs -l /dev/mmcblk0p1
[sudo] password for summers:
tune2fs 1.45.6 (20-Mar-2020)
Filesystem volume name: <none>
Last mounted on: /
Filesystem UUID: be7e43d4-37bb-4c2e-93e0-7710c0901743
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 1954064
Block count: 7814912
Reserved block count: 390745
Free blocks: 4195750
Free inodes: 1359894
First block: 0
Block size: 4096
Fragment size: 4096
Group descriptor size: 64
Reserved GDT blocks: 1024
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8176
Inode blocks per group: 511
Flex block group size: 16
Filesystem created: Sat Mar 10 16:18:42 2018
Last mount time: Sat Jan 1 00:00:03 2000
Last write time: Sat Jan 1 00:00:03 2000
Mount count: 101
Maximum mount count: -1
Last checked: Sat Mar 10 16:18:42 2018
Check interval: 0 (<none>)
Lifetime writes: 251 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 32
Desired extra isize: 32
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: 40714e2c-8d3b-4adc-8eef-f02b2bb75072
Journal backup: inode blocks
')
ls -l /boot
$this->bbcode_second_pass_code('', 'ls -l /boot/{MLO,u-boot.img}
-rw-r--r-- 1 root root 78672 Mar 11 2018 /boot/MLO
-rw-r--r-- 1 root root 390536 Mar 11 2018 /boot/u-boot.img
')
Reason for looking at sizes, is I note that your 2020 uboot has quite a lot of functionality. We only have 1MB space before the first partition, and the offset of uboot is 384kB - so uboot can only at most be 600kB. Mine is only 390kB, so fits easilly - half wonder though if yours is too large.
Anyway post results here, and we can compare with what I go above, and see any differences ...