AdiIRC

For 1), this is intended, when "Only show events from users active in the last [X] minutes" is enabled, join/part/nick/quit messages are only shown from users who have spoken in the last X minutes. The ideas behind this feature is users only care what happens to other users they are currently speaking to or reading messages from.

For 2), if you have "Ignore timestamp for consecutive times" enabled, all messages (except the first) with the same timestamp will not have a timestamp. Same timestamp means if you have a 4 messages with the timestamp of [20:44], only the first of these 4 messages have a timestamp. This option affects all types of messages and is purely based on the timestamp itself, while "Ignore timestamp for consecutive messages" only affect user messages from the same user.

There might be a bug here, if I understand correctly, a user joins and imminently sends a message, the join is hidden but the message doesn't have a timestamp. If there is no previous message or event with the same timestamp, then that is a bug. I'll do some tests on that.