Hello. You can report bugs here: https://forum.paradoxplaza.com/forum/index.php?forums/hearts-of-iron-4-bug-reports.951/

Originally posted by Nelly:

Originally posted by PDX_Moderator_2: Hello. You can report bugs here: https://forum.paradoxplaza.com/forum/index.php?forums/hearts-of-iron-4-bug-reports.951/

Do you also read the hoi4 subreddit? Asking because of (potential) bug reports

There are community ambassadors that see content from twitter, reddit, facebook etc. Some reports can be overlooked, so it is always best to report it to the official bug report section where devs will definitely see it.