If you do a private message command like /whisper Madofado, and they already left, it will say “Player is not on the server!” or “Invalid player!” or something. However, if someone whispers to you, leaves, and you do /r or /reply, then it will still work, but send the message to no one.
As you can see here, the message sends successfully, but no one recieves it.
Further info: On mobile, on gamemodes, in a zombies match.
This is an ancient bug that has been known about for years.
It’s completely normal, and is probably never going to be fixed.
Makes sense, I assume these kind of things would happen a lot by accident.
This appears to be a tshock bug. You can report it here instead
However, a TShock update(for the server) may take a while due to some major changes in TShock.
Could you elaborate?
for example, bans system was slightly tweaked
there are also other complications with updating to 1.4.1.2 like dimensions + mobile
Is mobile updating from 1.4? I haven’t kept up with the news
It already has, it’s just that there’s some complications with 1.4.2 servers and dimensions
I mean to 1.4.1 not 1.4, or has it already updated to that too? I can’t find anything about it, everything about 1.4.1 is PC-only.
I believe it’s still on 1.4
Reported 
This is fixed as of TShock 4.5.1. However it’ll be a while till the servers update to that version.