I tried the rebuild again and it didn't fix it. The source files have not moved and the paths match. I'm working with two related projects simultaneously, and now the second project is exhibiting the same problem whereas it was working just a day ago. This makes it tough to debug.
I cannot step through source c code, only disassembly. When I set a breakpoint in main() for example, the code breaks at the breakpoint but then if I "step into" it always goes to the disassembly window. I've been using embedded studio for a number of months without this problem, but it has now become an issue. It happens with both the debug and release builds, but only with this project. Other projects step through c code just fine.
When I do a debug build, I get the message "main.o: plugin needed to handle lto object". What does that mean? How to fix it?