Whitespaces can be visible if you set "Show Whitespace Characters" on.
I have two suggestions for this whitespace character.
1. Change the color of whitespaces characters.
It is difficult to distinguish between a middle point character ("・") and the whitespace characters, which is also a middle point. If the whitespaces use different color than other characters such as gray, it will be easier to distinguish.
2. Change the whitespace character for full width to a square("□")
Half width whitespace character is a middle point. Full width whitespace character is also a middle point but at a little higher in height. In Japanese translation, there are often rules to use only either one of them. Currently, it is almost impossible to know which whitespace is used.