I have the same issue, tried an IsoAcoustic platform and it didn’t do much.
I then switched to a Townshend Audio Seismic platform and like @bdp24 I can highly recommend it. Their platforms are optimized based on mass, so you tell them how much your tt weighs and they tune the platform’s isolation to your particular tt.
A wall mounted platform is another potential solution, as others have mentioned but 1) it may not work for your setup in terms of reaching the turntable conveniently if mounted on a wall, 2) not everyone likes to have a turntable attached to the wall from a visual perspective rather than on a console or rack, and 3) how effective a wall mount is actually depends on your wall.
Just like floors, all walls are not born the same.

