I had this problem with a 32GB card as well. The partition layout was correct, just the ext4 filesystem doesn’t resize, and I think maybe because of the overlay, you can’t online resize, and you can’t obviously umount the root.
root@volumio /tmp/a/dyn: fdisk -l /dev/mmcblk0
Disk /dev/mmcblk0: 29 GiB, 31104958464 bytes, 60751872 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: 0x8d45ba47
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 * 1 187500 187500 91.6M c W95 FAT32 (LBA)
/dev/mmcblk0p2 188416 5468159 5279744 2.5G 83 Linux
/dev/mmcblk0p3 5468160 60751871 55283712 26.4G 83 Linux
root@volumio /tmp/a: df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mmcblk0p2 2.5G 500M 1.8G 22% /imgpart
/dev/loop0 446M 446M 0 100% /static
overlay 131M 123M 0 100% /
I removed the SD card, and ran the resize2fs with the SD card connected to my main system.
Expanded fine, so hopefully now I can get the touchscreen plugin installed and working.