SUMMARY


STEPS TO REPRODUCE
1. 
run xubuntu 19.10, then download and apt install 
partitionmanager (4.0.0-2)
libkpmcore8 (4.0.1-2) from https://packages.ubuntu.com/focal/admin/partitionmanager

2. unlock, and resize LUKS(1) ext4 partition (from 2.7TB to 6.3TB)


OBSERVED RESULT
after resize, partition has correct size, but not the filesystem. A resize2fs -p /dev/sdb needed to be executed to also resize the filesystem


EXPECTED RESULT
after resize, both partition, and fileystem have desired size

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: xubuntu 19.10 live CD with 4.0.0-2 packages to have latest partitionmanager 
(available in About System)
KDE Plasma Version: XFCE
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
I initially thought I created a LUKSv2 partition (that's why I wanted to run 4.0.0-2), but found out that back then I created a LUKSv1 partition. Anyway, the resize was thus wrong with LUKSv1

========= gdisk is:
Command (? for help): p
Disk /dev/sdb: 13673906224 sectors, 6.4 TiB
Model: LOGICAL VOLUME  
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): XXXX
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 13673906190
Partitions will be aligned on 2048-sector boundaries
Total free space is 2029 sectors (1014.5 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048     13673906175   6.4 TiB     8300  Linux filesystem


KDE Partition Manager: SMART Status Report
Date: 	31 Jan 2020 10:40:17
Program version: 	4.0.0
Backend: 	pmsfdiskbackendplugin (1)
KDE Frameworks version: 	5.62.0
Machine: 	Linux xubuntu 5.3.0-18-generic #19-Ubuntu SMP Tue Oct 8 20:14:06 UTC 2019 x86_64

Grow partition ‘/dev/sdb1’ from 2.73 TiB to 6.37 TiB
Job: Check file system on partition ‘/dev/sdb1’
Command: e2fsck -f -y -v /dev/mapper/ct
Check file system on partition ‘/dev/sdb1’: Success
Job: Set geometry of partition ‘/dev/sdb1’: Start sector: 2,048, length: 13,673,904,128
Command: sfdisk --force /dev/sdb -N 1
Set geometry of partition ‘/dev/sdb1’: Start sector: 2,048, length: 13,673,904,128: Success
Job: Resize file system on partition ‘/dev/sdb1’ to 13,673,904,128 sectors

Resizing file system from 5,860,243,471 to 13,673,904,128 sectors.


Command: cryptsetup resize /dev/mapper/ct

Resizing LUKS crypt on partition ‘/dev/sdb1’.


Command: resize2fs /dev/mapper/ct 5860239375s
Resize file system on partition ‘/dev/sdb1’ to 13,673,904,128 sectors: Success
Job: Check file system on partition ‘/dev/sdb1’
Command: e2fsck -f -y -v /dev/mapper/ct
Check file system on partition ‘/dev/sdb1’: Success
Grow partition ‘/dev/sdb1’ from 2.73 TiB to 6.37 TiB: Success