Svg sprites problem


I’m using sprite.svg on Mosh’s HTML and CSS course, part 3 building the website.
He provides all the svg icons in a folder and then I create a svg sprite file using one of the online
sprite generators.
All of them work except one (chevron) which just comes up as a black square.
Couldn’t figure it out at all so I decided to grab a free svg icon online similar and create a new sprite.svg file with that included.
Same problem occurs. All the other icons work fine but the new chevron svg I included in the new sprite.svg shows up as a black square too!
I can’t fathom it because in theory the two chevron svgs are totally none related.
I tried to take off all classes to make sure no CSS was messing things up but to no avail.
It’s driving me a bit mad haha. Hope someone can help.