I've created my world 5 or 6 updates ago and playing for a while. I've never encountered an allthemodium ore yet.Today I've got allthemodium sight with command and fly through the world in spectator mode while the effect is active.I couldn't find any after 15-20mins of searching. Than installed a xray mod to try if potionmaster mod doesn't show the ores or the problem is in allthemodium ore spawning.I got same result.No allthemodium ores are present in my world.I can use some help finding out if I am too unlucky finding them or something is wrong with my world creation.(idk if there is a command for finding specific ore/block in minecraft world)

Have you tried to rally looking only into really high mountains? Every snowy mountain with height above 170 should have at least 1-2 blocks of allthemodium ore