Comment # 1 on bug 1174939 from Thorsten Kukuk

Works fine for me:

 5  | single |       | Tue Aug  4 13:38:05 2020 | root | 130.77 MiB | number  |
Snapshot Update of #4 | important=yes
 6  | single |       | Tue Aug  4 16:37:47 2020 | root |   1.20 MiB | number  |
Snapshot Update of #5 | important=yes
 7  | single |       | Wed Aug  5 01:34:39 2020 | root |   1.87 MiB | number  |
Snapshot Update of #6 | important=yes
 8  | single |       | Wed Aug  5 12:33:16 2020 | root |   3.75 MiB | number  |
Snapshot Update of #7 |              
 9  | single |       | Wed Aug  5 12:34:09 2020 | root |   3.47 MiB |         |
Snapshot Update of #7 |              
10* | single |       | Thu Aug  6 01:03:25 2020 | root |   3.21 MiB |         |
Snapshot Update of #9 |              



As you wrote in the other bug report, snapper cannot set the quota for your
filesystem. Without quota, it's not possible for snapper to calculate the used
size.
You should find out why snapper is not able to set the quota on your system.