The LineSpace parameter available in the TOC (Table of Contents) block does not account for multi-line TOC entries. If LineSpace is set to 3 and there is a TOC entry that wraps a line, the space between that entry and the next will only be the equivalent of one blank line.

If your document has long TOC entries, make the appropriate adjustments to LineSpace to (a) achieve the desired spacing and (b) prevent lines from overlapping (a LineSpace of 2 and a TOC entry that wraps to 3 lines will overwrite the first line of the following TOC entry).