Just checked again. Updated chrome and restarted my laptop. Same, the floating button to multi-quote does not work at all in chrome, firefox is ok.
I can select and unselect the posts to quote, but pointer does not activate when move it on top of the floating quote button to actually do the quote
Also I think the floating notification about new posts to a thread did not work either (though not sure as just refreshed the page without investigating).
Any ideas what else I could do to get the floats in chrome working?