I have a Zabbix 4.0 and I have configured the MySQL template without problems.
For a new project we have installed Zabbix 4.4 and I can not configure MySQL template.

I followed the steps: https://www.zabbix.com/documentation/4.4/manual/config/templates_out_of_the_box/requirements/mysql

On the Zabbix server I check and see that it returns correct values:

/usr/sbin/zabbix_agentd -t mysql.ping
mysql.ping [t|1]

/usr/sbin/zabbix_agentd -t mysql.version
mysql.version [t|mysql Ver 14.14 Distrib 5.5.56, for linux-glibc2.5 (x86_64) using readline 5.1]

/usr/sbin/zabbix_agentd -t net.tcp.listen[3306]
net.tcp.listen[3306] [u|1]

On Zabbix Server I got wrong values:
Host MySQL
Trigger MySQL: Service is down
Severity High
Problem expression {mysql-01.XXXXX.com:mysql.ping.last()}=0