Hello,

There is propably bugs in Maintenance periods. visible after upgrade to 5.4.1

Steps to reproduce:

1. Create Maintenance Mode period, for groups of hosts. 
2. Upgrade zabbix to 5.4.1
3. Observe zabbix behavior and Be dissapointed. 

Result:
 As result I can observe, that there are bugs on Maintenance mode in zabbix 5.4 

Bugs means that it is not working as expected. 

Example:

1.  Maintenance period is configured  for group of hosts,  daily 03:00 - 04:00 ( servers ar restarting daily)  we are receiving all mails about restarts during maintenance mode

• result : maintenance mode not working as expected.

2. Maintenance mode set for all groups for 1 hour period ( for test) 

after enabling all problems in "Problems" tab are  in Resolved State. ( no old problem visible)

• result : maintenance mode not working as expected.

Expected:

1.  Maintenance period is configured  for group of hosts,  daily 03:00 - 04:00 ( servers ar restarting daily)  we are receiving all mails about restarts during maintenance mode

• expected : do not receive mails alerts  during maintenance period

2. Maintenance mode set for all groups for 1 hour period ( for test) 

after enabling all problems in "Problems" tab are  in Resolved State. ( no old problem visible)

• expected : all problems visible in Problems tab,  new problem generated during maintenance period visible with maintenance key icon.