The workarounds are either older versions of the game and no longer relevant, or referring to other locations than Naxx (Lots of issues with Arathi Basin or CoS that are worked around or based on misunderstandings).
I’d be curious to know if anyone has been able to place a Love Fool in Naxx starting with resets this Tuesday (2/4) - As I’ve not yet met a single person who has claimed to have been able to do it since then. I have met people who were able to do it during this Love is in the Air, but the holiday launched Monday and the ones I’ve seen are people who did it as soon as they were on the day of the Holiday.
I’m seriously suspecting something broke it on Tuesday for EVERYONE. But if anyone has actually gotten it to work, let us know.
Also, OP & anyone else experiencing the issue, please submit an in-game bug report and comment on one of the threads in the Bug Report forums to try and get some visibility on the issue and get it fixed before the holiday ends.