FUSE-based filesystems are somehow ignored

[bjo81]

I tried backing up a juicefs-mount with rustic v0.11.1, after some discussion on Discord it's still unclear if the files are really backed up.
The data is around 160GB now, but according to rustics output, only 13 GB and 2 files are backed up, which are some database dumps outside of these mountpoints.
To rule out an issue with juicefs (while backing it up with restic months ago was no issue) I mounted a S3-repo with geesefs:

There is some data within the mountpoint:

# ls /mnt/immich/immich/chunks/0/195 -alh
insgesamt 233M                                                                                
drwxr-xr-x 2 root root 4,0K 30. Mär 11:51 .                                                   
drwxr-xr-x 2 root root 4,0K 30. Mär 01:14 ..                                                  
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_0_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_1_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_2_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_3_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_4_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_5_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_6_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_7_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_8_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_9_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_10_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_11_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_12_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_13_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_14_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195159_15_4194304
-rw-r--r-- 1 root root 256K 30. Mär 11:48 195160_0_262144 
-rw-r--r-- 1 root root 256K 30. Mär 11:48 195161_0_262144 
-rw-r--r-- 1 root root 236K 30. Mär 11:48 195162_0_240987
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195314_0_4194304
-rw-r--r-- 1 root root 4,0M 30. Mär 11:48 195314_1_4194304

So I ran rustic --log-level debug backup /mnt/immich/immich/chunks/0/195 and rustic said it justed backed up nothing and there is nothing:

[INFO] using parents 8d93a159
[INFO] starting to backup /mnt/immich/immich/chunks/0/195 ...
[00:00:10] backing up...                  ████████████████████████████████████████        0 B/0 B        0 B/s        (ETA -)                                                                
[DEBUG] changed   tree:  13 B
[00:00:10] backing up...                  ████████████████████████████████████████        0 B/0 B        0 B/s        (ETA -)                                                                
[INFO] Files:       0 new, 0 changed, 0 unchanged
[INFO] Dirs:        0 new, 1 changed, 0 unchanged
[DEBUG] Data Blobs:  0 new
[DEBUG] Tree Blobs:  0 new
[INFO] Added to the repo: 0 B (raw: 0 B)
[INFO] processed 0 files, 0 B
[INFO] snapshot e292b8ba successfully saved.
[INFO] backup of /mnt/immich/immich/chunks/0/195 done.