I have a Extreme Pro USB 3.1 128GB SSD. I can install Catalina on it just fine using a Macbook Pro 15" 2015, and it will boot on the SSD after the OS is installed. BUT, the latest OS security update will NOT install properly on the SSD, it just hangs the machine forever. I think it’s a flaw in the SSD design, because a Samsung T5 works just fine.
Any suggestions? I have a feeling asking SanDisk to replace it will give the same result.