When I tighten the truss rod in the neck it increases the bow. When I completely loosen it the neck goes “almost” flat. So long as it stays that way I’m not too worried but if it starts to bow it doesn’t appear I can adjust it out???
A one-way truss rod only counteracts up-bow (relief). Tightening a one-way rod is supposed to flatten an up-bowed neck. Loosening a one-way rod lets the neck get pulled into up-bow by the strings. But a one-way rod cannot set any amount of up-bow.
A two-way rod, on the other hand, can both flatten a neck and introduce relief.
If you can "tighten" a nut (clockwise) and see increased bow but can't turn the nut the other way past a neutral position to create flatness and even backbow, then you might need to have a luthier look at this. And you might be looking at an expensive repair.
I am NOT recommending that you turn the nut further than it wants to go. That's the absolute worst thing to do. But something does not sound right.