Not assigned to project after entering US

Hi,
I am on H1B visa and have an approved I-140. I have some questions on my situation. I was working for CompanyA and I left US in April 2022 and went to India and my employer CompanyA relieved me in August 2022. Thereafter I transferred my H1B to another employer CompanyB in May 2023 while I was still out of country and did not work for CompanyB while in India and have I797B. Now I have entered US in January 2024 since my employer CompanyB had a project for me. But CompanyB has still not assigned me on a project and neither submmited I-9 form. In this situation what can I do, can I transfer H1B to another employer Company C? And what are my options ? Also a note my previous employer CompanyA H1 is valid until June 2024.

Thanks.

You can’t be benched and not paid while on H1B status. Talk to your managet/HR to immediately start your employment.
If you are willing, you can complain to DOL and USCIS so they can file charges against your employer if they are not paying you.

To change the employer aka transfer , you need last three paystubs which is not available as you aren’t paid yet by your current employer.