How to Fix the External Flash Drive Become Read-Only on Mac Issue?

Hi there, I can definitely tell you that the Sandisk Cruzer Titanium USB flash drive not recognized issue does not only happen to you. Actually, a Mac user who met the same trouble and then emailed SanDisk, receives SanDisk's reply, reading, "We have found that Apple made some significant changes to the USB stack in 10.7 (Lion) so it no longer supports the Cruzer Enterprise Mac modules. Unfortunately, the entire Cruzer Enterprise product range was issued end-of-life in November 2011. As such, there is no further product development, so there is no fix or workaround for this issue."

Based on the reply, I suggest you downgrade your macOS or only utilize your external hard drive on other Mac computers. Good luck!