Hi @bruno,
I’ve looked at the code and this is indeed a problem to fix.
Initially, the changeCovarianceType() was designed to return an error because it would necessarily be expressed in Cartesian (for non-inertial frame) but it turns out that this may be a bit too punishing for the user in addition to causing this issue. I’m going to add a check so that it can work if the type is changed from Cartesian to Cartesian (useless indeed but not impossible nor false).
I’m opening an issue about this and I’m going to work on it ASAP.
Cheers,
Vincent