Image src won't change in exported HTML

GrapesJS version

• I confirm to use the latest version of GrapesJS

What browser are you using?

chrome 100

Reproducible demo link

https://grapesjs.com/demo.html

Describe the bug

How to reproduce the bug? 0. I am using external

1. Drag an image block to canvas
2. Select an image from the custom modal
3. View the code
4. Check the model/target object attributes

What is the expected behavior? The src attribute of the exported code should contain the actual url <img src="actual-url" />

What is the current behavior? I am using an external module for custom asset manager.

The model/target src attribute should contain the actual url <img width="682" alt="Screen Shot 2022-04-08 at 2 26 08 PM" src="https://user-images.githubusercontent.com/48402616/162377084-c1eff1fe-3084-468e-8f27-ea287dda62f6.png">

but the exported html has the placeholder base64 as src attribute <img width="616" alt="Screen Shot 2022-04-08 at 2 35 55 PM" src="https://user-images.githubusercontent.com/48402616/162378381-861f5a70-0857-4fe2-a0f6-cec1d13182ab.png">

If is necessary to execute some code in order to reproduce the bug, paste it here below:

The config:

assetManager: {
        custom: {
          open: (props) => {
            this.showAddMedia = true;
          },
          close: (props) => {
            this.showAddMedia = false;
          }
        },
      },

Adding the src attribute

 setMedia(doc) {
  const selected = this.editor.getSelected();
  selected.addAttributes({ src: doc.url });
  console.log(selected)
  console.log(selected.toHTML())
  this.editor.AssetManager.close()
},
closeMediaModal() {
  this.editor.AssetManager.close()
}

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