Why can't my iMac read RAW files from my sandisk SD card?

Hi, I bought a new iMac for a better performance for my photography business and it cannot read the RAW files (.CR2) on my SD card. It will read the card, but it will not read the raw files. A few random will be read, but the rest cannot be open, seen or read. (2/1000 will read) Sometimes, the files will show empty even though I know there's a 1000 raw files on the SD card. It's like my iMac cannot recognize or read the raw images. I have tried 3-4 different Sandisk & Emtec cards and it's the same problem. (see 3 attachments for examples)

for the last 6 months, I have been transferring the raw files to my Macbook pro (laptop) to then transfer it to an external drive, and then load it to my iMac. it's such a long process and I am worried for the moment my laptop gives out, how will I be able to transfer the raw files to my iMac. My laptop has no trouble at all reading the raw files from the same SD card that cannot be read by my iMac.

When I made the purchase in June 2020 I believe, I had ordered an iMac but it wasn't the right fit for what I needed, so I had to return it for one that would better suit my needs. The same problem occurred on BOTH iMac's.

My husband has even called apple support to fix this issue but even they didn't know how to help us.

I'm so desperate for answers. Please can anyone help me with this?

Extra info:

I shoot only in raw (.CR2) on my Canon 5D Mark iv (I never shoot in jpeg)

SD card info: Sandisk extreme PRO 170 MB/S, V30, SDXC, 3, class 10, 128 GB

thanks in advance,

Angele