What is my legal status while my I-485 for EB-5 is pending but the EB-5 RC program is on hold?

Stay on that H1B. USCIS: "We will begin rejecting all Forms I-485, Application to Register Permanent Residence or Adjust Status, and any associated Forms I-765, Application for Employment Authorization, and Forms I-131, Application for Travel Document, based on an approved Regional Center Form I-526."

My understanding is that in this interim the I-485 will pend but not be adjudicated. Certainly safest to maintain the H-1B if you can.

Yes, they are holding adjustments in abeyance, but maybe not the best time to quit your H-1B.

If you give up your H-1B, you will no longer have any nonimmigrant status in the United States. Based on your pending I-485, you are in a period of authorized stay and not accruing unlawful presence for purposes of the 3/10 reentry bars.

Yes, you would be considered in a period of authorized stay as long as your I-485 remains pending. The temporary lapse of the program does not impact your ability to stay in the US. Having said that, maintaining your H-1B status is still a preferable option in most circumstances.

As of right now, your pending I-485 would give you authorized stay, but I would advise keeping your H1B status.

If it is retroactively returned, and if people who filed are not automatically denied, perhaps you can proceed without maintaining H1B status. And if not, USCIS will deny the applications and you will have no legal status.