Today we got a custom flag that had no associated message. After conversing with the user who created the flag, the repro steps were something like this:
Send a Message to the author of a post via the Flag Post UI.
Reopen the Flag Post UI to submit a Custom Flag for the same post.
Note that the text from the Message is still there. Since you want to send the same text in the Custom Flag, submit as-is.
Think all is well with the world until a staff member sends you a message asking what your custom flag without a message is all about.
Because no message chain is created, no communications can be tied to the flag directly.
I fixed. The fix is just to reset the form after the first flag is successfully submitted. It wasn’t intended that the same message would be pre-filled for next flag.