Cannot allow a single folder in /mnt

[danielkrajnik]

I'm trying to provide access to a single folder inside /mnt. noblacklist /mnt works (all folders in /mnt become available). But noblacklist /mnt/folderA doesn't work (no folders in /mnt are available).

It's a wine application launched with:
firejail --include=/home/user/.config/firejail/wine-everything.local --profile=wine --env=WINEPREFIX="/home/user/.wine-everything" wine "C:\Program Files\Everything 1.5a\Everything64.exe"

wine.local:

whitelist ${HOME}/.wine-everything
whitelist ${HOME}/.cache/winetricks
whitelist ${HOME}/.cache/wine
whitelist ${HOME}/Desktop
noblacklist /mnt/folderA
net none

I've tried whitelist /mnt/folderA, but then the application fails:

Reading profile /home/user/.config/firejail/wine-everything.local
Reading profile /etc/firejail/wine.profile
Reading profile /home/user/.config/firejail/wine.local
Reading profile /etc/firejail/disable-common.inc
Reading profile /etc/firejail/disable-devel.inc
Reading profile /etc/firejail/disable-interpreters.inc
Reading profile /etc/firejail/disable-programs.inc
Reading profile /etc/firejail/whitelist-var-common.inc
Parent pid 3379230, child pid 3379241
Warning: cannot open source file /usr/lib/firejail/seccomp.debug32, file not copied
Warning: NVIDIA card detected, nogroups command ignored
Warning: cleaning all supplementary groups
Warning: NVIDIA card detected, nogroups command ignored
Warning: cleaning all supplementary groups
Warning: NVIDIA card detected, nogroups command ignored
Warning: cleaning all supplementary groups
Error fstat: fs_whitelist.c:156 whitelist_file: Permission denied
Error: proc 3379230 cannot sync with peer: unexpected EOF
Peer 3379241 unexpectedly exited with status 1

/mnt contains a lot of FUSE-based mounted filesystems (rclone, mergerfs). Could it be a problem?

[kmk3]

What is the version of firejail and wine?

Does it work with the following?

ignore disable-mnt
noblacklist /mnt
whitelist /mnt/folderA

What is the output of the following?

ls -l /mnt/folderA

firejail --ignore=disable-mnt --profile=wine \
  --noblacklist=/mnt --whitelist=/mnt/folderA 
  ls /mnt

Does it work if you disable all customizations in .local files etc?