I think this works for both "updated" and "updateddate".
To determine issues "updated in the last X" you must use "> -X" ("greater than negative X ago"). Why?
Trying to use "< X" ("less than X ago") seems to utterly fail. I tried "<100d" for 100 days and was getting issues updated many years ago.
My question is not how does the syntax work, as I get it now, but why does it work this way? Why doesn't `less than` actually work?