Configure postfix after Mailman 2 to 3 migration

I'm new to postfix. Maybe someone can guide me towards a solution.

I did the migration from mailman2 to 3 according to the official site, everything was imported correctly. However, I found that lists do not work for me in the new version. Emails sent by users are not processed. Only the confirmation emails are being delivered correctly. The old mailman still handles everything correctly. They are on the same instance by the way(Ubuntu 18.04).

If I understand correctly, I need to change the postfix configuration somehow.

I generated new lists and alias databases:

/var/lib/mailman3/data# mailman aliases 
/var/lib/mailman3/data# cat postfix_lmtp

# Aliases which are visible only in the @ xxxx.xxxxx.com domain.
[email protected] lmtp: [127.0.0.1]: 8024
.......
.......
.....

and added a file with new aliases via postmap then

#postmap /var/lib/mailman3/data/postfix_lmtp

After, I added new files with aliases to alias_maps and ailas_database in main.cf

smtpd_banner = $ myhostname ESMTP $ mail_name (Ubuntu)
biff = no

append_dot_mydomain = no

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination

readme_directory = no

# TLS parameters
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree: ${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree: ${data_directory}/smtp_scache

myhostname = xxx.xxxx.com
alias_maps = hash:t/etc/aliases, hash:/var/lib/mailman3/data/postfix_lmtp
alias_database = hash:/etc/aliases, hash:/var/lib/mailman3/data/postfix_lmtp.db
myorigin = /etc/mailname
mydestination = xxxxxxxxx.xxxxxx.com, localhost, localhost.localdomain, localhost
relayhost =
relay_domains = /var/lib/mailman3/data/postfix_domains
mynetworks = 127.0.0.0/8, [:: 1]/128, actual_server_ip
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all

milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet: localhost: 8891
non_smtpd_milters = inet: localhost: 8891

local_recipient_maps =
luser_relay = [email protected]

transport_maps = hash:/etc/postfix/transport
slow_destination_recipient_limit = 5
slow_destination_concurrency_limit = 2

Now I have run out of ideas on how to get mailman3 to work. It is not important for me to save mailman2, I will be ready to get rid of it as soon as mailman3 is working.

UPD: I started to receive mail, but mailman3 does not send them to lists. For some reason, it sends it to a specific mailbox instead. Below is a part of mail.log that shows how a message sent to the mailman3 list is handled. There are no errors in mail.err and mailman.log.

/var/log/mail.log
    postfix/smtpd[24824]: connect from xxxx.com
    postfix/smtpd[24824]: A30EB1171B: client=xxxxx.com
    postfix/cleanup[24827]: A30EB1171B: message-id=<[email protected]>
    opendkim[24800]: A30EB1171B: xxxxx.com  not internal
    opendkim[24800]: A30EB1171B: not authenticated
    opendkim[24800]: A30EB1171B: DKIM verification successful
    opendkim[24800]: A30EB1171B: s=20161025 d=xxxx.com SSL
    postfix/qmgr[20609]: A30EB1171B: from=<[email protected]>, size=12738, nrcpt=1 (queue active)
    postfix/cleanup[24827]: D91391179B: message-id=<[email protected]>
    postfix/local[24829]: A30EB1171B: to=<[email protected]>, relay=local, delay=0.23, delays=0.22/0/0/0.01, dsn=2.0.0, status=sent (forwarded as D91391179B)
    postfix/qmgr[20609]: D91391179B: from=<[email protected]>, size=13112, nrcpt=1 (queue active)
    postfix/qmgr[20609]: A30EB1171B: removed
    postfix/smtpd[24824]: disconnect from xxxxx.com ehlo=2 starttls=1 mail=1 rcpt=1 data=1 quit=1 commands=7
    postfix/smtp[24771]: D91391179B: to=<[email protected]>, orig_to=<[email protected]>, relay=xxxxx.com []:25, delay=0.52, delays=0/0/0.05/0.46, dsn=2.0.0, status=sent (250 2.0.0 OK  1624661277 dz4si5042577qvb.36 - gsmtp)
    postfix/qmgr[20609]: D91391179B: removed