AdiIRC

I am not able to reproduce this, try with /scripts off or a clean adiirc.

It seems on Rawlog the debug is there, i tested on clean adiirc.

The cases when comma is added on 1st parameter is working, it doesn't only if 1st parameter target is 1 item, like /msg westor test-bug or /msg #testing_2 test-bug

-> 27/4/2022 12:05:36 - @label=0066 PRIVMSG westor :test-bug
<- 27/4/2022 12:05:36 - @label=0066 :irc.valware.uk ACK
-> 27/4/2022 12:05:40 - @label=0067 PRIVMSG #testing_2 :test-bug
<- 27/4/2022 12:05:40 - @label=0067 :irc.valware.uk ACK

I am not able to reproduce.

When specifying more than 1 targets using comma, /msg westor,#testing_2 test adiirc prints/echo (27/Apr/2022 12:12:03.739) -> *westor,#testing_2* test
But doesn't prints/echo if you don't use any comma, /msg westor test adiirc doesn't print/echo anything, it just sending the message.

have you looked in the private window it opens?

Yes, i checked target windows to verify, its nothing there, the message is being send correctly but doesn't prints/echo anything, it works for /notice

For example in /notice:

[12:18:05] -> -westor- test1
[12:18:22] -> -#testing_2- test2
[12:19:01] -> -westor,#testing_2- test3

Not sure what's up for you, but it works as expected for me<

You mean when you use /msg nickname test you see adiirc echoing [12:17:51] -> *nickname* test ?
Or if you use /msg #channel test you see adiirc echoing [12:17:51] -> *#channel* test ?