Limit_days filter doesn't work

This is parameters i use:

st_tag_cloud(‘cloud_selection=count-desc&cloud_sort=random&number=5&largest=14&smallest=14&unit=px&maxcolor=#54AAF5&mincolor=#54AAF5’);

and it’s ok, but if i add:

&limit_days=30

or every other number, tag cloud show only 1 tag. why?

https://ww.wp.xz.cn/plugins/simple-tags/