Can't load html file with LoadHTMLGlob in production build. It's working in development

I'm using the Go Gin package in my rest-API service. To add some data I used HTML file to submit the form with data. In development, it's working, but in the production build server not working, if I commented 'LoadHTMLGlob' block server working again. I think 'LoadHTMLGlob' can't load HTML. Please help to solve this issue.

my main.go file:

package main

import (
    "ct-merchant-api/Config"
    "ct-merchant-api/Routes"
    "fmt"
    "github.com/jinzhu/gorm"
)
var err error

func main() {
    Config.DB, err = gorm.Open("mysql", Config.DbURL(Config.BuildDBConfig()))

    if err != nil {
	    fmt.Println("Status:", err)
    }
    defer Config.DB.Close()

    r := Routes.SetupRouter()
    
    // Load HTML   
    r.LoadHTMLGlob("templates/*")
    
    //running
    runningPort := Config.GetServerInfo()
    _ = r.Run(":" + runningPort.ServerPort)
}

Route file:

package Routes

import (
	"ct-merchant-api/Controllers/Referral"
	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
	"net/http"
)

func SetupRouter() *gin.Engine {
	api := gin.Default()
	config := cors.DefaultConfig()
	config.AllowAllOrigins = true
	config.AllowCredentials = true
	config.AddAllowHeaders("authorization")
	api.Use(cors.New(config))

	api.GET("/", func(c *gin.Context) {
		c.String(http.StatusOK, "Welcome to GO-rib Server")
	})

	api.GET("/referral/:merchantId", Referral.LeadForm)
	api.POST("/add-lead", Referral.LeadAdd)

	return api
}

Project Structure:

├── go.mod
├── go.sum
├── main.go
├── README.md
├── Routes
│   ── Routes.go
└── templates
|	── lead-add-response.html
|	── referral.html

For Deployment I Create a service go-web-api.service in /lib/systemd/system

In go-web-api.service file:

[Unit]
Description=goweb

[Service]
Type=simple
Restart=always
RestartSec=5s
ExecStart={my_project_build_file_path}

[Install]
WantedBy=multi-user.target

You need to add WorkingDirectory to your system file

[Service]
Type=simple
Restart=always
RestartSec=5s
WorkingDirectory=/path/to/your/project //add this line
ExecStart={my_project_build_file_path}