HDD on the verge of dying?
The best course of action is to use the secondary Linux machine to read the drive and make a bit-for-bit copy as soon as possible. Use a program such as ddrescue to ensure you get as possible out.

After you've made the copy, do any recovery attempts of file contents on the image you've created with ddrescue.

Your hybrid drive is most probably failing and failing fast. Hybrid drives have a lot more failure modes than a regular hard drive or SSD drive, so that's why you can experience very odd things happening - without for example it being the same sectors that are "bad" all the time.

You'll need to replace the drive. As it is only 6 months, perhaps you can get it replaced under warranty from the drive manufacturer or seller.