runMI function error: 'no slot of name "internalList" for this object of class "lavaanList"'

Question

I have run a multiple imputation (m=45, 10 iterations) using MICE and am attempting to fit a series of confirmatory factor analysis and structural equation models on the imputed datasets using the runMI function from semTools. Nearly all of my variables are Likert scales, coded as ordered/ordinal. Here is my code for the first CFA, where mi.res.train is the mice-generated mids object:

ipc_c_model <- '
IPC_C =~ t2IPC6_1 + t2IPC6_2 + t2IPC6_3 + t2IPC6_4 + t2IPC6_5 + t2IPC6_6 + t2IPC6_7'
ipc_c_fit <- runMI(ipc_c_model, mi.res.train, fun = "cfa", ordered = TRUE)

The model does not fit and returns the following error:

Error in slot(value, what) : no slot of name "internalList" for this object of class "lavaanList"

As far as I can see, the lavaan.mi object that this is supposed to create is a special type of lavaanList object. Any ideas as to what may be causing this error?

Thanks!