Issue with joining two objects

I couldn’t find anyone with a similar issue in the archives so I figured I’d ask here.

I made a low poly model using the mirror modifier.
I’d now like to sculpt some features. However, I discovered that the mirror modifier doesn’t work in sculpt mode, so I’d be working with half an object.
So, I figured I would turn off the mirror modifier, duplicated the object half, mirror it from the object menu, select both objects, and then join them.
After doing this, one side (the mirrored side) becomes see-through. Why might this be happening?
I’ve included an image of the problem. I have subsurf on there, but I’ve toggled it with no change.


Hopefully someone else has experienced this issue and can help? Or perhaps suggest a way of compensating for the lack of mirror modifier in sculpt mode?

Thank you

Try recalculating its normals by selecting all vertices and use Ctrl+N

This actually recreates the issue I’m having.

I determined what the problem was.
The issue was caused by having ‘Shading: Textured Solid’ selected.

Vinpocetine, sculpt does have mirror, check on the left there is a tab called symmetry. You can also create the other half with symmetrize by typing it in or pressing the button on the left.