Azure Function SQL Output Binding hangs on insert (Node.js) + need APIM policy to match OIDC oid/sub

I’m trying to insert rows into Azure SQL Database using Azure Functions SQL Output Binding (Node.js).

const { app, output } = require('@azure/functions');
const { z } = require('zod');

// SQL Output Binding
const sqlOutput = output.sql({
  commandText: 'dbo.coach_profile',
  connectionStringSetting: 'SqlConnectionString',
});

const coachSchema = z.object({
  first_name: z.string().nullable().optional(),
  last_name: z.string().nullable().optional(),
  bio: z.string().nullable().optional(),
  email: z.string().nullable().optional(),
});

app.http('create_coach_profile', {
  route: 'coach/create_profile',
  methods: ['POST'],
  authLevel: 'function',
  extraOutputs: [sqlOutput],
  handler: async (req, ctx) => {
    try {
      const user_id = req.headers['x-user-id'];
      const email = req.headers['x-user-email'];

      if (!user_id || !email) {
        return { status: 401, jsonBody: { error: 'Missing identity headers' } };
      }

      const body = await req.json();
      const validated = coachSchema.parse(body);

      const coach = {
        ...validated,
        user_id,
        email
        // not sending created_at / updated_at (SQL defaults handle these)
      };

      ctx.extraOutputs.set(sqlOutput, coach);
      return { status: 201, jsonBody: { success: true, coach } };
    } catch (err) {
      return { status: 500, jsonBody: { error: err.message } };
    }
  },
});

CREATE TABLE [dbo].[coach_profile](
  [coach_id] INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
  [user_id] NVARCHAR(100) NOT NULL,
  [first_name] NVARCHAR(100) NULL,
  [last_name] NVARCHAR(100) NULL,
  [bio] NVARCHAR(MAX) NULL,
  [email] NVARCHAR(256) NULL,
  [created_at] DATETIME2 NOT NULL DEFAULT SYSUTCDATETIME(),
  [updated_at] DATETIME2 NOT NULL DEFAULT SYSUTCDATETIME(),
  CONSTRAINT [UQ_coach_profile_user] UNIQUE ([user_id])
);

Executed 'Functions.create_coach_profile' (Failed, Duration=240001ms)
Error: Failed to fetch

Why does Azure SQL Output Binding work for one table but hang for another?

Do I need to explicitly include the PK even when it’s IDENTITY?

Could the UNIQUE constraint on user_id cause a silent failure?

How can I enable more detailed logging for SQL Output Bindings?