Lightroom is cropping my images when importing (RAW)

One year after you post:

You are not alone in this miserable unaddressed Adobe problem.

I've experienced it for years, and there doesn't appear to be any logical answer other than Adobe programmers dump previous camera and lens profiles whenever Adove issues new iterations of Adobe software; thus leaving Camera Raw hamstrung and saddled with Jpeg data.

The Adove Camera Raw data is still in the file, retrievable by other NON Adobe Programs (somewhat reassuring), but why won't Adobe offer a definitive and progressive solution in their products interface?

I've been trying to find the same answer to your question with Adobe Photoshop CS5 through CS Cloud 2020 Camera Raw 6.2 -through 12.2. All Adobe Raw processing programs do the same thing - crops the edges of RW2 data  and flattens the lens vision.  - In essence stripping the photograph of its analog (human) presence,  everything that differentiates it from a digital image (developers, good enough).

All that said.. try this: The author addresses the issue, from another camera, but the solution may help you because its geared toward Lightroom: https://helpx.adobe.com/lightroom-classic/kb/canon-5d-mark-iii-images.html
I haven't gathered them all but -Here are some other questions sked and unanswered posts:

Problums with raw files being cropped: https://community.adobe.com/t5/photoshop/problem-with-raw-files-being-cropped/m-p/9413873?page=1#M120513

Images unexpectdly cropped https://community.adobe.com/t5/photoshop/problem-with-raw-files-being-cropped/m-p/9413873?page=1#M120513

More of the same: https://community.adobe.com/t5/lightroom-classic/raw-files-being-cropped-upon-import/td-p/8984329?page=1

Good luck.