Basic Harm macro not working?

So for several expansions i have been using the standard mouseover macro for most of my help and harm spells (see below). However, recently I have found that if I select my target and mouseover nothing, the macro says I have no target. If I then mouseover the target it works just fine. It seems that the fallback [] condition no longer works? It also does not work if I change [] into [@target]. Anyone else?

#showtooltip
/cast [@mouseover] [] SPELL

You’re missing an existence check.

Interesting. This is new to dragonflight then because my macros have not changed since before shadowlands and they all of a sudden have stopped.