Light Select max number??

I have 21 light select render elements available when using LightMix
But going back to my scene I need to add more but they dont show up in the VFB just the original 21

New ones are in my Render Elements list available in the outliner with lights dropped into set but dont appear.

Is there a maximum amount you can use?
Only need to add 5 more LS elements

As far as I know, the limit is 64 individual light selects (including Environment and Self Illumination). Testing on a simple scene this seems to be true. In your case, something else is happening. Mind if you send the scene so we can troubleshoot?