@elan42
Yes, the <
character is considered the opening of an HTML tag and our data sanitizer (HTMLawed) thinks it's bad HTML hence why it strips the character and remaining content. With this being said, we hope to do a lot better in v2.0 with a completely new and modern sanitizer. This way we can allow such characters even code blocks, markdown, etc.
As @ntozier said, the only workaround for now is to edit the core files but this will have a chance of introducing XSS and other major attacks so it's not recommended.
Cheers.