In the latest version of rxode2 (>= 2.0.12), messages are output in the console because of this FAKE omega matrix which is passed to the rxSolve method (as a reminder, ETA's are generated by Campsis and used as covariates in RxODE/rxode2/mrgsolve) . A simple workaround now with rxode2 is to use omega=FALSE.
In the latest version of rxode2 (>= 2.0.12), messages are output in the console because of this FAKE omega matrix which is passed to the rxSolve method (as a reminder, ETA's are generated by Campsis and used as covariates in RxODE/rxode2/mrgsolve) . A simple workaround now with rxode2 is to use omega=FALSE.