Copy link to clipboard
That subject link says it all. Do you USE THEM or NOT?
I tried a few and each time it caused weird and strange things to happen, nothing that had anything to do with a slide's transition.
Could this be a leftover of SWF? And that's why they aren't working as advertised when you Preview in HTML5 Browser?
Did you check the HTML tracker under Project menu? You'll see that slide transitions are not supported for HTML output. Some may be functional on desktop/laptop, but no guarantee at all.