I placed a station in Interstellar space. I docked in and had couple of mission screens displayed. Refueled and launched from the station, then magically I am in the original targeted system not in interstellar space. Interstellar space station in my six.
I tried this behavior with 1.75.1 and later with 1.75.0, I remember that was not a problem with an earlier nightly, because I tested Eric's Acheanar with it.
You need to add the new interstellar_undocking key into its shipdata.plist and set it to true/yes.
The docking and jumping when undocking "feature" is a long known semi-bug, which was worked around with the key above in 1.75. But presumably for backward consistency, it was set to false/no by default.