Hi Cheryl.
Sorry about the screencast - I don't know what happened with that. I did however record a new one because snaps were used accurately and I wanted to show you the result.
https://autode.sk/39wJrFU
On zooming, the snaps don't appear to be accurate but as you'll see - the loft completes successfully in one case, but not the other. Secondly, as I hover the cursor over one of the "disconnected" arc/splice conjunctions you'll see a ghostly duplicate appear/disappear. The working loft is mine and the one that does not work has been copied from a student. A few other students are also experiencing the same problem. As we are all working from home we have a quite a variety of hardware configurations.
I'll attach the .dwg file used in the screencast as well (2007 format) as requested by "Patchy".