...
Again, I don' t know why this happens, but this workaround seems to do the trick. Let me know what obstacles you run into and I'll see if I can work them out.
A second issue that arose in Summer, 2016: After importing a dataset from csv, everything works until it's time to save. At that point, an error message arises. I used the same tactic described above...and I was able to generate intact layers...but once I re-load those saved layers, I see that they're useless – the imported data isn't there and the polygons of the layer have lost their data.
What I ended up doing: Import the csv. Then, before attempting to save the project, I export the data from that layer. I chose a dbf, but I don't know whether that matters. I found that the exported dataset would import and work properly with no saving errors.
I only experienced this on one project, so I don't know if there was something wrong with that csv file (but how? I looked at it in a text editor and it was clean, no formatting issues that I could spot) or if this a larger problem with My World.