My Mac (now running High Sierra) produces exactly the same error as you report. I don't know if it is actually related to the problem as in my post - I don't understand SWP 6 sufficiently well to tell. But I note that, when double-clicking on where your image should be, the box "Expression to be plotted" under the "Items plotted" tab is blank, which might have something to do with your problem.

If I recall correctly, version 6.0.26 actually worked better for plotting and for including graphics than 6.0.27. So if you are in a hurry, you might try reverting to SWP 6.0.26.

I find it deeply frustrating that nobody at MacKichan has commented on this issue. My experience is that, as it stands, SWP 6.0.27 is completely useless for anything to do with graphics and plotting, which seems to me an absolutely fundamental flaw in a product for which the ability to use these are a major selling point. SWP 6.0.26 was somewhat better, though still not very satisfactory. But in over 19 weeks, there has been no indication from anybody at MacKichan of when there will be a version of SWP 6 available that actually handles something that is supposed to be a fundamental feature of the program.

Can somebody at MacKichan **please** let us know when we will have a version of SWP 6 that handles graphics and plots satisfactorily?