1. The open and close times are difficult to set precisely had to do trial and error till it corresponded with Nigeria's time zone. And this varies for different instruments.
I set the values for XM, since i can't know for sure what broker you use i could not have set the values beforehand. It was intended for the user to set the value.
I agree some instruments need special tweaking we could simplify that process but since every broker is different you really can't have fixed default.
2. For some instruments the charts refuse to display when you change the session open/close times from the default.
Some instruments don't trade 24/7 there may be an issue there, you would have to let me know the exact instrument and broker for that.
Could you please give me the name of the instrument, and which broker is it. This will need addressing.
Workspace management:
You can manage various charts in MT5 add it to another chart where you just view the sessions. That way you can plot the levels on session. (see first image)
To answer a previously asked question, yes you would have to remove the indicator for chart to become normal.
I had posted an example of a chart where the candles don't vanish at all the selected session candles have a fixed color rest all show same color.(see second image)