This is happening to me as well, Logic immediately crashes whenever I open up SD3. From what I understand, 10.5 is crashing with other third party plugins as well (I think Native Instruments is having this issue too) – hopefully Apple fixes this ASAP.
Reply To: Logic Pro 10.5 causes SD3 to crash?! version: 3.1.7 Operating system: macOS Catalina (10.15)