Only first level of share are browsable

Hi, i have a strange issue, in my share I can only see the first level of the shares, for example I have the A B C folders, I see the files contained in A and not in B and C, if in A I have sub folders AA BB CC, I always see the files contained in AA and not BB and CC. I have investigated the logs and I have no errors, can you give me some advice on how to solve? Thanks in advance
Debian 4.19.37-5+deb10u2 (2019-08-08) x86_64
PHP 7.3.4-2
APC 5.1.17
MariaDb 10.3

In a first step I would recommend to check the directory ownership and access rights on the console, like e.g.:

# ls -ald A
# ls -ald A/AA
# ls -ald A/BB