ps5
The sledgehammer challenge to destroy a structure does not work with the exerimental sledgehammer.
I always thought that it could be related to the damage type the hammer does. With the experimental sledgehammer the damage type could be a different one. 
It’s a know thing and it’s not just a PS5 thing.
Today I went all in, both a augmented 5C and Expreimental sledgehammer. Used them in the other fmtel mission “do a easy base assult” up in Forest region, roamed around some other bases and finaly spent a couple of hours in the South coast area running between FNIX bases - nothing that could be destroyd triggerd that mission to complete.
I would probably hold off on fmtel unless they ever fix it. They said they were looking into the issue where it only gives you one point for every mission, but nothing yet