BIND 9.16, must stop named, delete .jnl files for signed zones to be updated

Summary

For a signed zone to be updated I have to stop named, delete all the "." files, update the serial number and then start named again. If I do a normal update, just update the serial number and then run "rndc reload", I got this error message "29-May-2021 13:54:52.008 general: error: zone ******.se/IN (signed): receive_secure_serial: unchanged", and the zone don't update. I have had this issue in previous versions also, now I run 9.16.16.

BIND version used

BIND 9.16.16 (Stable Release) <id:0c314d8>
running on Linux x86_64 4.18.0-305.el8.x86_64 #1 SMP Thu Apr 29 08:54:30 EDT 2021
built by make with '--prefix=/service/dns/bind-9.16.16' '--sysconfdir=/data/dns/named' '--localstatedir=/var' '--with-openssl=/service/dns/openssl' 'LDFLAGS=-ldl'
compiled by GCC 8.4.1 20200928 (Red Hat 8.4.1-1)
compiled with OpenSSL version: OpenSSL 1.1.1k  25 Mar 2021
linked to OpenSSL version: OpenSSL 1.1.1k  25 Mar 2021
compiled with libuv version: 1.23.1
linked to libuv version: 1.23.1
compiled with libxml2 version: 2.9.7
linked to libxml2 version: 20907
compiled with zlib version: 1.2.11
linked to zlib version: 1.2.11
threads support is enabled

default paths:
  named configuration:  /data/dns/named/named.conf
  rndc configuration:   /data/dns/named/rndc.conf
  DNSSEC root key:      /data/dns/named/bind.keys
  nsupdate session key: /var/run/named/session.key
  named PID file:       /var/run/named/named.pid
  named lock file:      /var/run/named/named.lock

Steps to reproduce

Update the serial number for signed zone och then do a "rndc reload"

What is the current bug behavior?

The zone doesn't update

What is the expected correct behavior?

The zone should be updated after I have changed the serial number

Relevant configuration files

I use a manually policy for signed zones, "dnssec-policy modified;"

dnssec-policy "modified" {
        keys {
                csk lifetime unlimited algorithm rsasha256 2048;
        };
};

Relevant logs and/or screenshots

"29-May-2021 13:54:52.008 general: error: zone ******.se/IN (signed): receive_secure_serial: unchanged"

Possible fixes

The workaround is to stop named, delete all "." files (.jbk, .jnl, .signed, .signed.jnl), update the serial number, start named again.