ConversationHandler issue with telegram python

Not being able to call /order twice. I call /order, without doing anything, i call /order again. It's not calling the async def order. It should work without allow_reentry=True. WHY?

ORDER_CATEGORY, ORDER_PRODUCT, ORDER_CART, ORDER_CONFIRM = range(4)
async def order(update: Update, context: ContextTypes.DEFAULT_TYPE):
    
    keyboard = [
        [InlineKeyboardButton("Insulin (အင်ဆူလင်)", callback_data='insulin')],
        [InlineKeyboardButton("Pill (ဆေးလုံး)", callback_data='pill')],
        [InlineKeyboardButton("Ozempic, Wegovy, Mounjaro", callback_data='injection')],
        [InlineKeyboardButton("Machine (ကရိယာ)", callback_data='machine')]
    ]
    
    # Create the markup for the inline keyboard
    reply_markup = InlineKeyboardMarkup(keyboard)
    
    # Send the message with the inline keyboard
    await update.message.reply_text('Choose an option:', reply_markup=reply_markup)
    
    return ORDER_CATEGORY

# Define the ConversationHandler
def order_handler():
    return ConversationHandler(
        entry_points=[CommandHandler('order', order)],
        states={
            ORDER_CATEGORY: [CallbackQueryHandler(category)],
            ORDER_PRODUCT: [CallbackQueryHandler(product, pattern=r'^\d+$')],
            ORDER_CART: [CallbackQueryHandler(cart, pattern=r'^\d+_qty_\d+$')],
            ORDER_CONFIRM: [CallbackQueryHandler(confirm, pattern=r'^confirm$')],
        },
        fallbacks=[CommandHandler('cancel', cancel)],
        allow_reentry=True # Should work without this. WHY?
    )

# Set up the Application and add the handler
async def cancel(update: Update, context: ContextTypes.DEFAULT_TYPE):
    await update.message.reply_text(text="Cancelled")
    context.user_data.clear()
    return ConversationHandler.END


def main():
    application = Application.builder().token(TELEGRAM_BOT_TOKEN).build()

    # Start
    application.add_handler(CommandHandler("start", start))
    # Order
    application.add_handler(order_handler())

    # Start the bot
    application.run_polling()

I tried with allow_reentry=True, obviously it works but it should be working without it.

I also tried removing the state, it works but won’t proceed to the next step.