It's specifically this: https://github.com/sproctor/compose-data-table/blob/main/datatable/src/commonMain/kotlin/com/seanproctor/datatable/Table.kt#L133

It doesn’t really work with a virtual layout like this, if you need to group multiple elements as one for the purposes of indication or otherwise

On a side note you’d probably find that it would make a bunch of stuff much better here: e.g you wouldn’t need to have this manual pointer input tracking logic, you could just add

Modifier.clickable

to each row, which would also properly implement accessibility that your current implementation doesn’t have support for.