Hi ,
I'm Dyari. Thanks for reaching out.
To verify that it is not a hardware-related issue, connect a wired keyboard to your computer and test to see whether it works or not.
You can also use the on-screen keyboard to see if the shift key works.
If the shift key works with both the on-screen keyboard and a wired keyboard, there may be an issue with the physical keyboard. Please hold the shift and release it multiple times. Clean carefully and check to see if it works.
Please keep me posted.