When making changes in the TOC dialogue box, if you just press "OK", the changes are only made until you next update the TOC (why?? Where's the warning??!) It's intuitive to expect that pressing OK is updating the TOC style permanently.
Instead, you need to press "Save Style" & go through the process of overwriting the style. OK should automatically overwrite the style & then you "Save Style" if you want to create an alternate.
I had a large print job stuffed up because of this. I know that others have mentioned this (but I couldn't go through 57 pages of search results to find it).

I also 'second' requests:

• IMPERATIVE - be able to resize the TOC dialogue box (even automatically to fit the length of the list) - this is currently frustrating & time-consuming to have to scroll through to find the correct Paragraph Style & not being able to see the entire name of them (other boxes were previously changed to allow this but this one was neglected);
• The ability to insert a set distance between the page number & the contents text to allow for automatic soft returns.

• HANDY - To be able to update the TOC from the right-click context menu when the TOC text box is selected; &
• Option to update TOC on export or close might be nice.