Thunderbolt 3 female to Thunderbolt 2 male adapter for Mac Pro?

I tried the exact same thing hoping it would work: Thunderbolt 3 to Thunderbolt 2 adapter plugged into a Thunderbolt 3 external hard drive, then connecting the adapter to my iMac's Thunderbolt 2 port via a male-to-male Thunderbolt 2 cable. The drive's LED light did not come on, nor was it recognized by my iMac. I contacted Apple support about it, and they sent me a new adapter and cable, which did not work either. Finally, after weeks of trying to follow up with the support supervisor who was handing my case, I got in touch with another support supervisor, who basically told me the adapters do not work going from Thunderbolt 3 devices into Thunderbolt 2 computer ports.

I asked if Apple had a solution, and he said "no", and that it was not Apple's issue, and that I should contact the manufacturer of the drive. He then said something about buying an Apple external drive to meet my need of running it on my two computers which have Thunderbolt 3 and Thunderbolt 1 ports, but I was too angry at that point to even consider that as a solution, since I wanted to use the expensive Thunderbolt 3 SSD I had already purchased, and did not want to buy another expensive drive.

It seems to me that Apple could create a solution to this if they wanted, but they do not want to. It looks like they just want to make more money by forcing customers to buy more of their products.

Thanks for the explaining the technical limit to the adapter, Grant! However, I am still wondering about jjtiziou's original question: Does someone make a Thunderbolt 3 female to Thunderbolt 2 male adapter? Or is there some other solution available? I have searched all over and cannot find anything.

The first case number is 100157086728, but the problem was miscategorized, and I was having all sorts of issues getting responses from the support supervisor who originally helped me, so I started a new support case, numbered 100181204249. I hope this helps.

Also, if you find a solution, jjtiziou, please let me know, as I would really like to get my drive working with my iMac. Thanks!

I do not understand the dilemma.

can you not:

Plug the Apple adapter USB-C end directly into the Lacie unit, and

plug a thunderBolt-2 cable (male-to-male) into your computer and the adapter?

Are you running Sierra (required for this adapter) ??

Drives used in this way need their own power supply -- they cannot be simply Bus Powered, because the adapter is "facing the wrong way" to provide bus power to the drive.

That said, they still may not work if other reports above are accurate.