For whatever reason attempting to use connect=material in a ctm.properties file doesn't seem to affect anything. Shown here is the normal set of copper blocks connecting to themselves, but not the other types. The intended behavior would be that the edges would simply make a perfect square. I have also tried this with other block types such as dirts (Dirt, Coarse Dirt, and Rooted Dirt) and got the same results.

This value was removed from both Optifine and Continuity in 1.20. It will not be added back as the code that made it possible was completely removed in vanilla 1.20.

So do we just not have this option anymore? If there's another way to accomplish this now it would be much appreciated if you could inform me how.

There is no alternative other than the other available values for connect (state, block, and tile) at the moment. I plan to add additional features eventually.