Not useless when you can see invisible enemies... which I can. So not sure what to tell you.
Then the RNG was clearly in your favour, but that's
not how See Invisibility is supposed to work. I burned an elixir of see invisibility on a character with expertise in perception at 11th-level and saw
nothing, I had to have my party light the whole room up with fireballs and alchemist's fire to find anything, so that was even
more resources wasted. And even then I somehow missed one who remained hidden after combat ended and then killed an NPC.