How to correctly use ProgressDialog around a WriteAction

Hello, I can't get the threading correct for my WriteAction correctly working with ProgressDialog.

What I want: show a ProgressDialog while running ReadAction, WriteAction, and commits.

What's happening: I either get a PD showing but also threading errors from my WriteAction or I get no PD showing but writes do occur.

My code looks something like this (simplified, full code on my GitHub):

ProgressManager.getInstance().runProcessWithProgressSynchronously(
{ doWork(ProgressManager.getInstance().progressIndicator.modalityState) },
...)

private fun doWork(modalityState: ModalityState) {
    val app = ApplicationManager.getApplication()
    val elementsToModify = app.runReadAction<List<PsiElement>> { find() }

    app.invokeLater(
        {
            executeCommand(project = project) {
                app.runWriteAction {
                    elementsToModify.forEach { 
                        writeModifications(it)
                        it.containingFile.commitAndUnblockDocument()
                    }
                }
            }
        },
        modalityState
    )
}

Full code at https://github.com/hbmartin/intellij-kotlin-bulk-add-name-params/blob/main/src/main/kotlin/com/github/hbmartin/intellijkotlinbulkaddnameparams/BulkAddNamedParamsAction.kt

Thanks,

Harold