valueFormat="object" refreshes v-model after select or new option (vue treeselect)

Question

I have a problem here. I don't know if this is a bug or what but here's my issue.

Upon loading my component, I'll assign a selected value to the v-model that is used in the plugin.

So, here's my selected values.

     ofcSelected:[
      {
        id: 65,
        label: "Tagum-Mabini",
        category: 'core_functions',
        children: null
      },
      {
        id: 44,
        label: "OSAS",
        category: 'core_functions',
        children: null
      }
    ],

and I have this category object (I don't know if this is right to have a custom object for the selected values) but when I try to select or deselect options in the plugin, category object will be removed. It will look like this.

ofcSelected:[
  {
    id: 65,
    label: "Tagum-Mabini",
    children: null
  },
  {
    id: 44,
    label: "OSAS",
    children: null
  }
],

I think it resets the selected object based on the options. Do I have any way to keep the category object even after selecting or deselecting other options?

I hope you can help. Thank you!