Thanks for the reply
That seems like a pretty good description of what I've done - checking the page the correct tracking code is inserted with no whitespace or other shenanigans that'd ruin everything. I guess that's no surprise since it worked for a day.
That's the main thing throwing me off, if it hadn't worked at all then that'd make more sense :/
Also the bit on the page view that displays whether it's receiving data or not is just blank. I've seen it say "receiving data" and I've seen it say "code not found" and other error messages - but I've never seen it simply absent before.