Mbed Studio - debug doesn't follow source

Hi. I’m using Mbed Studio 1.4.3 on Mac OS 11.2. The mbed-os libraries are updated to 6.15.1. The tools appear to be all up-to-date. Using armc6 compiler for a FRDM-K66F.

When I debug a program, I expect the source code viewer to follow the current line in the source code, starting with the first line in main(), but it’s not. When I type “next” in the debug panel, the source code view doesn’t change. It’s nearly impossible to tell where in the program I am at a given time. “list” in the debug panel sometimes shows source code, but it’s not useful if I don’t know how I got there from a “next.” I did change the “-O0” setting in debug.json, but that didn’t help.

Any suggestions?