[seodisparate]

"When stuck debugging, question all of your assumptions about the program."

A shower thought. Helpful if the program does something other than what you thought it did, allowing you to figure that out quicker.

[mjevans]

More a reflection of insufficient logging telemetry at higher inspection (debugging) levels.

If you have the above and still can't figure it out, maybe you're looking at too much. Sometimes it can help to isolate which stage things appear to go off the rails and then turn up the detail when you've got an idea where to start the search.