Cleanse claims to stop all disables but it wont stop the suppression of a malz ult or a ww ult.
As the description says Removes all disables and summoner spells debuffs affecting your champion and grants 65% crowd control reduction for 3 seconds.
Suppression prevents the use of Summoner Spells; therefore, you are unable to clense. QSS works to remove it though.
This is working as intended.
Cleanse isn't supposed to remove suppressions in the first place, although you can make an argument that it should.
That is the difference between a supression and a stun.
