Same behavior here with 16.04. On boot and on upgrades the systems ask me for the password. If I use solution from #59 the system don't ask for the password anymore but the system takes 2 minutes to boot.

lino@pioneer:~$   sudo blkid
/dev/nvme0n1p6: UUID="d987f11f-51ab-446c-9cad-65f27200bd1f" TYPE="swap" PARTUUID="26ba4f5f-272f-4b52-8c95-fb32a025bada"
/dev/nvme0n1p1: LABEL="ESP" UUID="BC3B-4E24" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="423cce4f-51be-4c8f-a38c-7f35c4f25ad6"
/dev/nvme0n1p3: LABEL="OS" UUID="01D1865215EBF300" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="82f7b959-5b3d-4979-9ed9-275e7aa27135"
/dev/nvme0n1p4: LABEL="WINRETOOLS" UUID="44B2596EB2596608" TYPE="ntfs" PARTUUID="bd62ca2b-7eb9-47e9-a6dd-d7546be31a08"
/dev/nvme0n1p5: LABEL="Image" UUID="EA9459D89459A7B9" TYPE="ntfs" PARTUUID="814b3f7f-53f7-41aa-8b1f-bdef9ac64932"
/dev/nvme0n1p7: UUID="3c2d5db4-6381-4f81-9599-5d29942c917a" TYPE="ext4" PARTUUID="7b96edbd-a17d-4481-8cf7-ec31d165e182"
/dev/sda1: LABEL="CODEMETER" UUID="002B-D004" TYPE="vfat" PARTUUID="002bd004-01"
/dev/sdb1: SEC_TYPE="msdos" LABEL="DellUtility" UUID="3030-3030" TYPE="vfat" PARTUUID="07f2837e-01"
/dev/sdb2: LABEL="RECOVERY" UUID="92D03605D035EFD9" TYPE="ntfs" PARTUUID="07f2837e-02"
/dev/sdb3: UUID="defefa91-e453-4f67-85e2-8402447ef8fb" TYPE="crypto_LUKS" PARTUUID="07f2837e-03"
/dev/mapper/luks-defefa91-e453-4f67-85e2-8402447ef8fb: LABEL="Disco_Externo" UUID="597f766f-7dee-478c-a512-b49ecdf57843" TYPE="ext4"
/dev/nvme0n1: PTUUID="195d2663-e6e9-424d-ab66-31ec8f1d10a7" PTTYPE="gpt"
/dev/nvme0n1p2: PARTLABEL="Microsoft reserved partition" PARTUUID="ea83be62-bd92-4e6c-a98a-d652a9a003b1"
lino@pioneer:~$   swapon -s
Filename				Type		Size	Used	Priority
/dev/nvme0n1p6                         	partition	15999996	0	-1
lino@pioneer:~$   printf "x\np\n" | sudo fdisk /dev/sda

Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): 
Expert command (m for help): Disk /dev/sda: 39.3 MiB, 41156608 bytes, 80384 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: 0x002bd004

Device     Boot Start   End Sectors Id Type      Start-C/H/S End-C/H/S Attrs
/dev/sda1  *       63 80324   80262  b W95 FAT32       0/1/1  4/63/254    80

lino@pioneer:~$   ls -l /run/systemd/generator/
total 16
-rw-r--r-- 1 root root 374 Apr  1 07:21 boot-efi.mount
drwxr-xr-x 2 root root  60 Apr  1 07:21 cryptsetup.target.requires
drwxr-xr-x 2 root root  60 Apr  1 07:21 dev-disk-by\x2duuid-d987f11f\x2d51ab\x2d446c\x2d9cad\x2d65f27200bd1f.device.wants
drwxr-xr-x 2 root root  60 Apr  1 07:21 dev-mapper-cryptswap1.device.d
drwxr-xr-x 2 root root  60 Apr  1 07:21 dev-mapper-cryptswap1.device.requires
-rw-r--r-- 1 root root 188 Apr  1 07:21 dev-mapper-cryptswap1.swap
drwxr-xr-x 2 root root  60 Apr  1 07:21 hwclock.service.d
drwxr-xr-x 2 root root  80 Apr  1 07:21 local-fs.target.requires
drwxr-xr-x 2 root root  60 Apr  1 07:21 local-fs.target.wants
-rw-r--r-- 1 root root 277 Apr  1 07:21 -.mount
drwxr-xr-x 2 root root  60 Apr  1 07:21 multi-user.target.wants
drwxr-xr-x 2 root root  60 Apr  1 07:21 networking.service.d
drwxr-xr-x 2 root root  60 Apr  1 07:21 remote-fs.target.d
drwxr-xr-x 2 root root  60 Apr  1 07:21 sendsigs.service.d
drwxr-xr-x 2 root root  60 Apr  1 07:21 swap.target.requires
-rw-r--r-- 1 root root 947 Apr  1 07:21 <email address hidden>
drwxr-xr-x 2 root root  60 Apr  1 07:21 umountfs.service.d
drwxr-xr-x 2 root root  60 Apr  1 07:21 umountnfs.service.d

lino@pioneer:~$ cat /etc/fstab 
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/nvme0n1p7 during installation
UUID=3c2d5db4-6381-4f81-9599-5d29942c917a /               ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/nvme0n1p1 during installation
UUID=BC3B-4E24  /boot/efi       vfat    umask=0077      0       1
# swap was on /dev/nvme0n1p6 during installation
#UUID=d987f11f-51ab-446c-9cad-65f27200bd1f none            swap    sw              0       0
/dev/mapper/cryptswap1 none swap sw 0 0
lino@pioneer:~$ cat /etc/crypttab 
cryptswap1 UUID=d987f11f-51ab-446c-9cad-65f27200bd1f /dev/urandom swap,offset=1024,cipher=aes-xts-plain64
#cryptswap1 /dev/disk/by-uuid/d987f11f-51ab-446c-9cad-65f27200bd1f/dev/urandom swap,cipher=aes-cbc-essiv:sha256