LaCie RAID drive no longer detected on Macbook Pro (Intel, 2019)

SituationRed wrote:

I've tried different ports, different wires, and a different, older Mac (that I also updated) but that couldn't see it either, so I'm suspecting a software update to Sonoma 14.2.1 might be something to do with it.

I am assuming that the older Mac also was updated to 14.2.1 ... correct? If so, have you tried updating to 14.4 yet?

When the drive is connected to either Mac, see if it appears in System Information:

• Hold down the Option Key, and then click on the Apple Logo on the macOS menu bar.
• Select System Information
• Select either Thunderbolt or USB under the Hardware category, depending on what port you connect this drive to.

Does the LaCie appear at all?

If I understood you, you also tried connecting the LaCie directly to your MacBook Pro ... correct?

If so, I know that the 2019 15" MacBook Pro comes equipped with four Thunderbolt 3 ports. The LaCie you have has a number of different ports, as well. I am assuming that you tried connecting from the LaCie's USB 2.0 to one of these USB-C ports with the appropriate adapter ... correct?

Do you have any other computers that you can connect the LaCie directly to, to verify that it can be recognized? If it can, then the issue may not be the LaCie itself, but with how you are connecting it to your Mac.