Hi,

I still do not understand if the problem is mismatched concepts between software

Baselines are nothing else the coordinate differences in a specific but known frame, i.e., $\Delta X = X_2 - X_1$. GNSS is refereed to WGS84. So, if you don't use any settings, the raw data are refereed to WGS84. For that reason, RTKLib must support WGS84 out of the box. Your baselines are not refereed to WGS84. You have select some settings to convert the raw WGS84 coordinates to something else.

a software bug

No, because I have tested several examples like this. It works fine. The problem is, that your coordinates are not congruent to your baselines. JAG3D needs congruent data (refereed to the same frame or an congruent frame).

I can produce new data to other goverment CORS or to private poins using a pair of GNSS receptors.

Please provide WGS84 coordinates and baselines (or use at least the same convention for both, the coordinates and the baselines).

/Micha