Thumbnail not showing

Support
1

Hi,
I just realized that the thumbnail not showing after selecting the photo file. Here is the exported data (.json)

 [
  {
    "name": "Teacher Name",
    "address": "Sample Address",
    "group": "teacher",
    "photo": {
        "path": "img\/teachers\\3.jpg"
    },
 ]

The thumbnail is appear after I replace (import) the data using

[
{
    "name": "Teacher Name",
    "address": "Sample Address",
    "group": "teacher",
    "photo": {
        "path": "img\/teacher\/3.jpg"
    }
]

Are there any settings that I missed?
I am using Windows + XAMPP + PHP 7.4 + Latest CockpitCMS