LDAP quota is ignored

Hello, I have just upgraded from dovecot 2.3.x to 2.4.0. I converted the configuration files and all is ok, but there is this strange thing about quota.

I have quota limit from LDAP:

quota_storage_size = %{ldap:quota}G

Value is correctly retrieved from LDAP, with "doveadm user user@domain":

quota_storage_size 10G

In configuration files of dovecot I have nothing about quota definitions. If I check in webmail I have undefined value.

If I set manually in configuration files:

quota "User quota" { storage_size = 1G }

quota is correctly shown in webmail, but only with this default value. It appears it ignores values from ldap userdb. How can I debug this? Thanks.