I think I'm having the same problem

Since upgrading from version 3.6.4 to 3.7.2 loading at once on tree grids do not seem to be working correctly.

The data loads into the grid correctly by when I click on a row to expand it out nothing happens.

If I set the rows to be expanded, they show expanded with the correct sub rows showing but clicking on the top level row does not collapse it.

It looks like it maybe something to do with the event that is fired when expanding the row. As far as I can tell the event is being triggered and run but it has no effect on the grid

Rolling back to the previous version of jqGrid solves the problem.

I have tried with both JSON and XML with no success.

If I load the sub rows on demand it seems to work correctly, but this is not what I want. I want to be able to load all rows and sub rows at once.

I would really like to be able to use the latest version as it has some bug fixes that I require.

Cheers

Rowan