Greasy Fork

Ignore this, I was stupid

Any idea why?

You didn't follow instructions to reduce the spacing in the top of the file as noted in the description. At the top of the code is this. These libraries are required without them you won't see timestamps, only the post information, like the ID etc. Remove the GAP between @ and r. Notice that there is a space separating @ and r the the last 2 lines of code here? Remove that space. It is in place as per GreasyFork's policy of not accept external references to JS Libraries. Moment.js is hosted on another website and is required for the timestamps.

// @require https://greasyfork.org/scripts/12228/code/setMutationHandler.js // @ require https://momentjs.com/downloads/moment.min.js // @ require https://momentjs.com/downloads/moment-with-locales.min.js

I feel like a complete idiot now; thanks!

Lol, it's alright most people don't read a script and they just click install and expect it to work, it happens.