Note: This bug is different from the original invisible-in-F8 bug (which is suspected to be caused by eye distance upon character creation and it still currently exists). This one is relatively new. I noticed the message around the March 17th, 2021, so it was likely the patch prior to this date. I hoped that UE4 launch would fix it, but it did not.
Characters with long IGNs will be invisible in F8 for every other player. "Long" means a character whose name is at least 13 characters. Invisible means everybody else is unable to see you. You will always be able to see yourself, but nobody else will be able to see your character (or its portrait at the top).
When you go into F8 with a long name, you will see this message in the chat box: "Unable to send. The message is too long." And everybody else in the party will not be able to see you.
Message from having a too-long name:
My character has an IGN that's long (Captain PewPew) and is met with this message each time it enters F8 and every time the party composition changes.
The following are screenshots from the perspective of two different clients. Both these characters have the exact same character build and equipment on. One has a short name and the other has a long name. "WitoPew" was created using the character appearance file from "Captain PewPew."
POV of short-named character:
This is the perspective of my character, but with a short name (WitoPew). As you can see, "Captain PewPew" is invisible.
POV of long-named character:
This is the perspective of my character, but with a long name (Captain PewPew). As you can see, "WitoPew" is visible
As you can see, the character with the short-name is visible, but not the one with the long-name (remember you can always see yourself on your own client). I have tested this with my other characters with long IGNs and have received the same results. Additionally, every time I see random people in F8 with 13+ long IGNs, they are also invisible. In fact, the new F8 icons from the recent solo event dungeon boarder will be visible, but not characters with long names.
POV of my friend's character:
My character "Shifting Blades" (with a long IGN) is invisible, but still has the title boarder.
This is very frustrating because I made my characters to be seen by others. A lot of people run dungeons with characters off, so this is one of the few places to be seen.
I hope NCSOFT fixes this bug soon or at least offers free name changes for those effected by this bug. Similarly how they gave out free appearance changes for characters who are invisible due to the original invisble-in-F8 bug.