Hi @Echulion, welcome
This is expected behaviour as -190 = 170 - 360, so it is really the same angle. See this post for a throrough explanation.
What error do you get for perigee argument and anomaly? If your orbit is very close to circular, then the perigee location is singular and you may end up with perigee argument increased by some random angle (say 10°, but can really be anything) when the anomaly is decreased by the exact same amount. What is stable, though is the sum ω+v. In other words if one propagator gives ω=100° and v=32° and the other propagator gives ω=110° and v=22° for a circular orbit, it is just because the perigee is not defined for this orbit, but both results are consistent. In this case, one should use other representations like CircularOrbit or EquinoctialOrbit (or stay with CartesianOrbit).
This is correct behaviour. The SGP4 propagator is not a Keplerian propagator it includes some approximations of mean evolution of a few forces. This implies that instantaneous position given by a TLE propagator cannot be used as an initial orbit for another propagator, regardless of the model you use. If you attempt to compare it to a Keplerian propagator, you will miss the perturbations SGP4 uses internally. If you attempt to compare it to a numerical propagator, SGP4 will miss the accurate definition of forces. In addition in both cases, you will be comparing osculating parameters when SGP4 provides mean parameters. The order of magnitude of the short periodic terms between these two models are of the order of magnitude of several kilometers, this is what you observe.
If you want to go from TLE to anything else, rather than just use one point you should use a full model conversion over several orbits (typically one day). There is a tutorial about that.