A table of contents is a special kind of text frame. It may not follow the rules of Smart Reflow.
Span column is used to make the text cross multiple columns in a single text frame (or its converse, divide a single column frame into multiple columns). It can interfere with many other text flow features. Why do you have it enabled here?
While placing Table of content to page, just select the shift + click on respective page where you want to place TOC. This will auto flow the contents by adding new Text Frames and pages with threading text frames.
In an earlier thread on this forum I was told that was needed in order to make text flow from first to subsequent columns in stories containing multi-column pages. Will turn that off now, thanks.