[Ulmo] Unit navigation bar missing next and previous icons

I am using Tutor V21.0.0. I just found that the icons for the previous and next do not show up in the unit navigation. Attached below is a screenshot for reference.

I would love to write a fix for this, but I am having a hard time figuring out where this piece of code is coming from and which repository I should fix it in.

#root .sequence-container .sequence .unit-navigation a svg, 
#root .sequence-container .sequence .unit-navigation button svg { 
display: none; 
}

Edit: I am using the tutor-indigo theme.

Could you try disabling Indigo and see if the issue is still there without Indigo?