Confirmed by at least 3 regular farmers.
I haven't had a WU drop in mitaar/Vortexx in about 4-5 days now.
Approximately 25-30 rounds with no drop.
Normally I get one in 10-12 rounds max and often within 1-4 rounds.
Two people have independently corroborated my observations.
First person records drops and he did 36 rounds of vortex with 1 drop and the second person who is a regular farmer as well observed that they 'don't seem to be dropping' which is the same as my observation.
FURTHER to this, if you look at spambot sales, there are no WU's for lootright sales in last several days.