"Allow HTML tags" is missing

I want to experiment with adding conditional scripted cell colors on some views. I understand I need to check "allow HTML tags" in the app settings. However, this checkbox is MISSING in the app I am working on as well as one other app but it present in 5 other apps I have created. I cannot understand the reason why it would be missing, however, when I try and apply HTML tags to cell text, the HTML tag is shown in text, which is, of course, not what I want.

Any ideas here?