Lemme Show You How To Not Find Witch Raid Here Are The Few Steps:
Step 1:Kill A Illager Captain When You Have A Bad Omen (Only Spawn In Pillager Outpost)
Step 2:Go To A Village When You Have A Bad Omen And The Raid Has Begin (i recommend to normal mode)
Step 3:Kill A Illager On Wave 1 And Wave 3
Step 4:When You Have A Wave 4 If You Heard A Horn There's A Issue But Now... There Is A 3 Pillagers Instead Of 3 Witches
Issue: Because The Raid Witches Has Nobody Here In Wave 4 (normal only) Or Last Wave (hard only)
Thank you for your report. We are going to track this at MCPE-149883 so I am resolving this report as a duplicate.