Request: online file modification in layers

I am testing fuse-overalyfs as an unionfs. I'm coming from unionfs-fusẹ. There are some file modifications (online, while mounted) that work in unionfs-fusẹ but not in fuse-overlayfs. I don't have the knowledge to determine if it is because of a bug, a different functionality or me? I'll be thankful if you help determine what it is. Let me present 3 cases. First, these are the steps to reproduce:

Directory layout for cases:

# parent directory
parent=$HOME/testing
lower=${parent}/lower
upper=${parent}/upper
target=${parent}/union
mkdir -p $parent
cd $parent

# target
mkdir -p $target

# lower directory
mkdir -p $lower
# lower directory files
echo "lower_dir1_var1" > ${lower}/file1
echo "lower_dir1_var2" > ${lower}/file2

# upper directory
mkdir -p $upper
# lower directory files
echo "upper_dir1_var2" > ${upper}/file2
echo "upper_dir1_var3" > ${upper}/file3

# mount them
fuse-overlayfs -o auto_unmount,lowerdir=${lower},upperdir=${upper},workdir=${parent} $target

Case 1: delete a file common to both layers

Delete file2 in the upper directory. File2 exists in the lower directory too, but with different value.

rm ${upper}/file2

Expected result in target mount point

Since file2 is deleted in the upper directory and not from the target mount point, I expected to see file2 in the target mount point but with content from the lower directory.

# cat ${target}/file2
lower_dir1_var2

Result in target mount point

File2 is listed but "No such file or directory" is shown also

# ls -al ${target}
ls: /var/home/job/testing/union/file2: No such file or directory
total 16
drwxrwxr-x. 2 job 4096 feb 29 12:55 .
-rw-rw-r--. 1 job   16 feb 29 12:55 file1
-rw-rw-r--. 1 job   16 feb 29 12:55 file2
-rw-rw-r--. 1 job   16 feb 29 12:55 file3

# cat ${target}/file2
cat: /var/home/job/testing/union/file2: No such file or directory

Case 2: add new file in the lower layer

Create a new file in the lower layer. The file does not exist in the upper layer.

echo "lower_dir1_var4" > ${lower}/file4

Expected result

I expected to see a new file4 with content from the lower layer

# cat ${target}/file4
lower_dir1_var4

Result

There is no file4 in the target mount point

# cat ${target}/file4
cat: /var/home/job/testing/union/file4: No such file or directory

Case 3: modified file in the lower layer

Modified the content of file1 in the lower layer. File1 does not exist in the upper layer.

echo "lower_dir1_var1_line2" >> ${lower}/file1

Expected result

New content from file1 in lower layer

# cat ${lower}/file1
lower_dir1_var1
lower_dir1_var1_line2

Result

Old content

# cat ${lower}/file1
lower_dir1_var1

Info

# OS
NAME=Fedora
VERSION="31.20200225.0 (Workstation Edition)"
# fuse
fuse-2.9.9-8.fc31.x86_64
fuse-common-3.6.2-1.fc31.x86_64
fuse-libs-2.9.9-8.fc31.x86_64
fuse-overlayfs-0.7.5-2.fc31.x86_64
fuse3-3.6.2-1.fc31.x86_64
fuse3-libs-3.6.2-1.fc31.x86_64
gvfs-fuse-1.42.2-1.fc31.x86_64

containers / fuse-overlayfs