Steps to reproduce:
1. Open JMC and a recording.
2. On e.g. the Java Application page, select about 20% of the total time in the middle of the chart.
3. Context click and select "Store and Set as Focused Selection".
==> The time range indicator above the table, below the selection area is not updated, it is still orange in the whole area.
The range indicator does get updated when you load a new page, so the workaround is to click on another page and then return.
I've also seen that the paining of the area is broken: I'll attach a screen shot of that problem.
Windows 7, 64-bit, JDK 9-146, JMC 6.0.0-642.