List View Formatting not letting me use grid-template (row or columns)

I'm trying to format a list view and can add "display": "grid". However, I'm having an issue trying to use grid-template-rows and grid-template-columns. It saves them to the JSON but when it renders in the browser those CSS properties aren't showing. I've tried on multiple browsers (Edge, Chrome, Opera, Firefox) and same issue. Sample of the JSON below:

"display": "grid",
"grid-template-columns": "30px 1fr",
"grid-template-rows": "30px 1fr",

If I use the developer tools it has display: grid; but the grid-template-columns and grid-template-rows don't exist at all. It's like they're just being ignored from the JSON when being rendered by SharePoint. Is this just a limitation of SharePoint Online and formatting where you can't use the grid CSS options? Seems a bit strange to me.