[Elements] hGrid excel export does not export child grid data

[IMinchev64]

Description

When trying to export a hierarchical grid to excel in angular-elements only the parent grid data and column headers are exported, while the child grid columns are not:

• "igniteui-webcomponents-grids": "4.8.0",
• "igniteui-react-grids": "18.6.0",
• "IgniteUI.Blazor": "23.2.199"
• browser: any

Steps to reproduce

1. Navigate to this sample
2. Export the grid to Excel
3. Expand the hidden rows

Result

The hidden rows are empty:

Expected result

Hidden rows should hold the data from the child grids:

Attachments

See screenshots above.

[IMinchev64]

This seems to also reproduce on latest master if on grid initialization the columns in a row island are disabled and later reenabled. Seems the columns array property is not updated after initialization.

On the contrary, columnList gets updated and contains all the columns at the moment of exporting the grid.