More interesting: 1. I made the sample file by copy/pasting the “corrupted task” to a new, blank schedule. Mark on Track also failed to have an effect in the sample schedule. On the next line of the sample schedule, I made a task with similar Actual Start and Duration. Mark on Track correctly advanced the progress line to the Status date. The environment has Project 2016 Pro.
2. I copied the “corrupted task,” went to another environment with Project 2010 Pro and pasted it in a new, blank schedule. The 22 Duration task appeared with a 12 workday bar followed by a dotted line out to the 22nd workday. Progress appeared through day 7, leaving 5 workdays incomplete on the shortened bar. Mark on Track had no effect. My experience is that a task that has a dotted line following the Gantt Bar is a corrupted task.
3. I copy/pasted the sample file to an email and sent it to myself on another machine that also has Project 2016 Pro. The “corrupted task” updated correctly with Mark on Track. So, I may have a cure.