It's working fine for me but I'm mounting my unionfs mount differently than you, it's mounted under /mnt/user/Media/Cloud/Movies instead of your /mnt/disks/Movies
####### Mount unionfs ##########
# check if mounted
if [[ -f "/mnt/user/Media/Cloud/Series/mountcheck" ]] && [[ -f "/mnt/user/Media/Cloud/Movies/mountcheck" ]]; then
echo "$(date "+%d.%m.%Y %T") INFO: Check successful, unionfs Movies & Series mounted."
rm /mnt/user/software/rclone_install_running
exit
else
# Unmount before remounting
fusermount -uz /mnt/user/Media/Cloud/Series
fusermount -uz /mnt/user/Media/Cloud/Movies
unionfs -o cow,allow_other,direct_io,auto_cache,sync_read /mnt/user/Media/Cloud/Seriestmp=RW:/mnt/disks/crypt/Series=RO /mnt/user/Media/Cloud/Series
unionfs -o cow,allow_other,direct_io,auto_cache,sync_read /mnt/user/Media/Cloud/Moviestmp=RW:/mnt/disks/crypt/Movies=RO /mnt/user/Media/Cloud/Movies
if [[ -f "/mnt/user/Media/Cloud/Series/mountcheck" ]] && [[ -f "/mnt/user/Media/Cloud/Movies/mountcheck" ]]; then
echo "$(date "+%d.%m.%Y %T") INFO: Check successful, unionfs Movies & Series mounted."
else
echo "$(date "+%d.%m.%Y %T") CRITICAL: unionfs Movies & Series Remount failed."
fi
fi