Create a creative world with this seed:
1191961552361
 
go to the nether:
/setblock ~ ~ ~ minecraft:nether_portal
 
go to this location:
/tp 725.01 57.00 -1071.62
 
then run this:
/locate fortress
 
 
In 1.18 it seems to find:
/tp @s 48 ~ -992
which is 681 blocks away
 
whereas in my 1.17.1 world it found:
/tp @s 960 ~ -1696
which is 666 blocks away
 
 
But the actual closest fortress is:
/tp @s 1008 ~ -1168
which is 299 blocks away

If you get closer, locate will eventually start finding this nether fortress