MxModel returns class MxRAMModel instead of MxModel?

I'm calling MxModel via do.call, with a list of arguments. Previously, this consistently returned objects of class MxModel. Now (probably after the latest OpenMx update), it returns MxRAMModel, which is inconvenient because not all exported methods work with MxRAMModel.

I'm rolling back my installation of OpenMx now to check if it's due to the latest update, but that takes a while.. in the meantime - does anyone know why I'm getting MxRAMModels and how to prevent that?

My full code is very extensive, but here's an example of the way I call MxModel:

  mxmodel_args <- list(
    model = "model",
    type='RAM',
    manifestVars = obs,
    latentVars = latent)
  out <- do.call(mxModel, c(mxmodel_args,
                     path_list))

Where path_list is a list of MxPaths.

Thank you kindly for your advice!