missing space after margin padding-spacing

[wini2]

When margin/padding is used (at least) in conjunction with alert or callout the markup shows
fsc-default ce-textmedia mt-5alert alert-primary instead of
fsc-default ce-textmedia mt-5 alert alert-primary

because it lacks of a spatium (t3sbs 5.3.22).
By the way: in 5.3.21 it works