JBOD Volume creation failed

You really shouldn't post log zip files publicly, so consider unsharing the zip.

Look in rn-expand.log

-- Logs begin at Sun 2020-03-15 15:57:40 GMT, end at Mon 2020-03-16 00:06:06 GMT. --
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: Creating pool: DISK2
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: * Level: 1
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: * Disks:
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: 	0:1 (sdb,ST4000VN008,3726GB)
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: prepare_disk: Prepare disk 0:1 (sdb,ST4000VN008,3726GB) with partition size 7804599872
Mar 15 15:58:35 nas-35-A8-1B rn-expand[2336]: Found sdb is not a member of root
Mar 15 15:58:42 nas-35-A8-1B rn-expand[2336]: Partitioning failed! [4]
Mar 15 15:58:42 nas-35-A8-1B rn-expand[2336]: output: Warning! Read error 5; strange behavior now likely!;Warning! Read error 5; strange behavior now likely!;Creating new GPT entries in memory.;Warning! GPT main header not overwritten! Error is 5;Warning: The kernel is still using the old partition table.;The new table will be used at the next reboot or after you;run partprobe(8) or kpartx(8);GPT data structures destroyed! You may now partition the disk using fdisk or;other utilities.;Warning! MBR not overwritten! Error is 5!;Warning! Read error 5; strange be
Mar 15 15:58:42 nas-35-A8-1B rn-expand[2336]: adding partition failed [5]
Mar 15 15:58:42 nas-35-A8-1B rn-expand[2336]: Found sdb is not a member of swap
Mar 15 15:58:43 nas-35-A8-1B rn-expand[2336]: Partitioning failed! [4]
Mar 15 15:58:43 nas-35-A8-1B rn-expand[2336]: output: Warning! Read error 5; strange behavior now likely!;Warning! Read error 5; strange behavior now likely!;Creating new GPT entries in memory.;Unable to save backup partition table! Perhaps the 'e' option on the experts';menu will resolve this problem.;Warning! An error was reported when writing the partition table! This error;MIGHT be harmless, or the disk might be damaged! Checking it is advisable.;
Mar 15 15:58:46 nas-35-A8-1B rn-expand[2336]: Partitioning failed! [4]
Mar 15 15:58:46 nas-35-A8-1B rn-expand[2336]: output: Warning! Read error 5; strange behavior now likely!;Warning! Read error 5; strange behavior now likely!;Creating new GPT entries in memory.;Unable to save backup partition table! Perhaps the 'e' option on the experts';menu will resolve this problem.;Warning! An error was reported when writing the partition table! This error;MIGHT be harmless, or the disk might be damaged! Checking it is advisable.;

And disk errors in kernel.log

Mar 15 16:20:51 Multimedia kernel: ata2.00: cmd c8/00:08:00:00:00/00:00:00:00:00/e0 tag 13 dma 4096 in
                                            res 51/04:08:00:00:00/00:00:00:00:00/e0 Emask 0x1 (device error)
Mar 15 16:20:51 Multimedia kernel: ata2.00: status: { DRDY ERR }
Mar 15 16:20:51 Multimedia kernel: ata2.00: error: { ABRT }
Mar 15 16:20:51 Multimedia kernel: ata2.00: configured for UDMA/133 (device error ignored)
Mar 15 16:20:51 Multimedia kernel: ata2: EH complete
Mar 15 16:20:51 Multimedia kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
Mar 15 16:20:51 Multimedia kernel: ata2.00: irq_stat 0x40000001
Mar 15 16:20:51 Multimedia kernel: ata2.00: failed command: READ DMA
Mar 15 16:20:51 Multimedia kernel: ata2.00: cmd c8/00:08:00:00:00/00:00:00:00:00/e0 tag 14 dma 4096 in
                                            res 51/04:08:00:00:00/00:00:00:00:00/e0 Emask 0x1 (device error)
Mar 15 16:20:51 Multimedia kernel: ata2.00: status: { DRDY ERR }
Mar 15 16:20:51 Multimedia kernel: ata2.00: error: { ABRT }

I suggest testing this disk in a Windows PC with Seatools.  Run the extended non-destructive test first.  If that passes, then run the full erase test.

I don't expect it to pass both Seatools tests - I think this disk has failed.  If this is a new disk, then try to exchange it with the seller - that will give you full warranty coverage on the replacement.