Uncaught Error: Cannot handle unknown node customInlineMath

[Innoviox]

I have the following code to create a custom math schema:

import { $nodeSchema } from "@milkdown/utils";

const mathInlineId = "custom_math_inline";

export const customMathInlineSchema = $nodeSchema(mathInlineId, () => {
  return {
    content: "text*",
    group: "inline",
    marks: "",
    defining: true,
    inline: true,
    attrs: {
      value: {
        default: "",
      },
    },
    parseMarkdown: {
      match: ({ type }) => type === "customInlineMath",
      runner: (state, node, type) => {
        state.addNode(type, { value: node.value as string });
      },
    },
    toMarkdown: {
      match: (node) => node.type.name === mathInlineId,
      runner: (state, node) => {
        state.addNode(
          "customInlineMath",
          undefined,
          node.attrs.value,
        );
      },
    },
  };
});

However, when I run it it will not save my nodes properly because I get the error:

Uncaught Error: Cannot handle unknown node customInlineMath
How can I tell it how to handle the customInlineMath node in a way that I have not already done? Everywhere I log the state.schema.nodes my node is in there, why is the handler not being found? How can I have a node of a custom type?