Angle brackets in planner task comment made task disappear
I'm not 100% certain that it is the cause but I added a comment to a task in one of our Planner tabs in a team and the noticed the text I had put in angle brackets "<" ">" did not show up. Then when I went back to the task later to show someone, the task has completely disappeared.
Sean Ellis commented
Probably because they are used for HTML tags. The same thing happens on Web Skype. Inputs should either be properly sanitized to convert these to HTML entities instead, or the message should be displayed without markup.