I can't guess. My usual find is the tech does do this often enough or the 1TB SSD was defective or tech was limiting themselves to 9.5MM high drives.
So any guess has to remain that with this little detail.
Can anyone tell me why Dell would tell me that I am only able to install a 256GB SSD On my computer that has a 1TB mechanical hard drive? I just don’t understand why I would have to drop so many gigabytes. Thank you