For "...B....C" it looks like:
&ARRAY# = B
&ARRAY# = C
Unlike in other script languages, multiple separators are not treated as one and there is no option to enable them to be treated as one. Also, the documentation it is not clear as to what happens in case of leading or trailing separators.
In the fix versions below the following text has been added to the documentaiton for the STR_SPLIT script function.
When multiple separator characters are used in a row, the STR_SPLIT script function creates empty strings for the second separator and all subsequent separators.
When a string begins with one or more separator characters, the STR_SPLIT script function creates empty strings for them.
Automation Engine Script Guide > Ordered by Function > Strings > STR_SPLIT