Advance Parole

While the status of Form I-485 is incomplete, and you have not gotten CPR status, advance parole allows you to travel from and return to the US.

The Effects of the US Federal Government Shutdown on the EB-5 Regional Center Program
Despite the shutdown, the USCIS will continue to operate and process all documentation associated with the EB-5 Program. Read more here.
A Ray of Hope for EB-5 Petitioners with I-526 Approvals - Especially from Retrogression Impacted Countries
The good news is that after approval there is a way you can stay in the United States with full working and travel rights, while you wait for your green card, even if your country has long waiting times.