I don't think you're doing anything wrong. When INS is in control, you shouldn't be able to change your heading. (About the only way I can assure myself that everything is working.) You can still tune NAV radios and adjust your course settings to verify your position, and that's independent of the INS. I think that's just the way it works.

Mark, thanks again.  I finally figured it out and realized it how this aircraft is meant to be navigated, it was a bug with the sim-pilot  , not the CSL1011.  Anyway, now that I know, I realize just how under-appreciated this CS-L1011 is.  There is something to do at practically every phase of flight.  It was really a marvelous airplane.  And this is a great simulation of it, and it looks fantastic in P35.1

Don’t worry about that. I don’t! The L1011 is so different from what we’re used to. As you probably know, the INS will give you distance and time to next waypoint. If you have a chart (I have Navigraph Charts on my iPad, which is also a neat cheat, since it displays your position) it’s not a bad practice to double check your position against nav aids off to the side. If your course takes you 20 miles to one side, then you had better be 20 miles DME from the selected nav aid at whatever radial you choose. I don’t know if the LROPS booklet is still available, but, if you can get a copy for download it has all sorts of procedures for Atlantic crossings—great for 757 or 767 too. I believe Captain Sim’s INS is 100% reliable, but if you aren’t comfortable with radio navigation you have more experiences to look forward to in this great airplane. If you’ve done the tutorial you’ll know what I mean.