I am pretty sure when occluded, it’s not meant to show through other objects? 
Sorry if I’m wrong!!
Expected behavior
I think it’s meant to be like this, though I havn’t used highlights in a while
(image found on google)
EDIT: It works fine during play test 
just bugs in studio
Just wanna note your Highlight structure isn’t correct, it’ll cause render stops pretty soon. Use a singular Highlight parented directly under your “letters” model.
Could this potentially be related to this bug? It seems like it could potentially either be related to this issue or it could even be the same issue you are unfortunately experiencing here.
Also, as mentioned in the above reply: if you don’t need seperate properties per-letter, to offset your chance of hitting the 31 highlight limit so early; you can use a singular highlight under the sign model in order to render the highlight. Putting a highlight under a model will result in the highlight rendering around the entire model while only using a singular highlight from the quota.
