UD formatted devices (same as unRAID formatted devices) are 4K aligned already, for advanced format devices and SSDs the partition needs to be aligned on a multiple of 4KB, they start at sector 64, so 64 x 512 bytes = 32 768 which is divisible by 4096, parted align-check is probably looking for a partition stating on sector 2048 (which would also be aligned). Besides, if your problem was an unaligned partition, you'd see the performance impact immediately, not just after an 80GB transfer, that doesn't make any sense, were you regularly trimming your SSD?