Of course as only one shuttle is used for the lock join, you cannot use the other shuttle/colour to hide the colour blip as I do in my blipless join. This needed to be explored... but the solution was simple in the end: using a Catherine Wheel Join solves the problem. If you look at the photo below, you can see that the CWJ is much neater looking as well as keeping the chain colour continuous.
One thing to take into consideration however is that the CWJ adds a stitch, whereas a lock join does not.
The problem with a CWJ though is that it doesn't "dip down" on the join like a lock join does. You can see in the photo above how much sharper the angle is on the lock join than it is on the CWJ. I found a solution: I make the last half stitch before the CWJ and the first half stitch after it with a double wrap which makes the base of the stitch larger and thereby giving a better shape to the join area.
I really like this way of making split chains which was shown to me by Marie Smith (see video). Before learning that method, I disliked tatting split chains and tended to avoid them even though, like split rings, they can be so useful when designing patterns and wanting to move from one round to the next without cutting and tying.
What I realised is that it's exactly the same movements to make a CWJ, as long as you make sure the other shuttle thread is in the right place. I will be making a new video showing this very soon. Hopefully others who may be struggling with the CWJ will find it useful too.
Best wishes,
Frivole