What should I do if I cannot make an Infopass appointment with USCIS for a visa stamp?

You should ask your immigration attorney to communicate with a person of authority in the USCIS office in San Diego about this situation.

Getting an InfoPass appointment is indeed challenging lately, but your only option is to keep trying (sometimes off-hours work best). If you live in an area where there are other USCIS district offices nearby, you can try if they allow for walk-ins.

Attempt to book an appointment very early in the morning or late at night, or keep trying multiple locations. Alternatively, have your attorney email the local field office to schedule due to lack of appointments online at various locations. This may work better.

Try scheduling an InfoPass appointment at the location nearest to your home address. If all booked, then your best bet may be to try a walk-in appointment (early morning is best). Good luck.

The apparent lack of help is unfortunate, but have your EB-5 attorney intervene in the process. There is no good justification for allowing the extension to lapse. Furthermore, most local USCIS offices allow walk-in InfoPass for emergencies. You should again try a walk-in and explain your urgent need.

I think all you can do is to keep trying. Everything immigration-related is way too slow and unresponsive, so sometimes persistence is all you have.

It is not clear to me why you are unable to make an InfoPass appointment unless the district office or field office of the USCIS is backed up and they can only give you an InfoPass appointment at some future date. I would suggest that you keep on applying remembering that you should apply at the district office that has jurisdiction of your place of residence.

Sometime appointments open at midnight. Unless you travel abroad or need proof of residency you do not actually need the stamp. You are a permanent resident until adjudicated otherwise.

Speak with an immigration lawyer to see if he/she can intervene and assist with obtaining your InfoPass appointment.

With the I-829 receipt notice only stating that conditional residency is extended for one year, not getting the stamp in the passport will pose a problem with traveling. Very few CBP officers at the various airports will know what your status may mean with the I-829 process. Try getting on the computer very early morning before 8 a.m. every day to try getting the InfoPass. My only other suggestion is to print out the current processing times from their website to carry that with you along with the I-829. However, this may not help you to avoid going through an extended interview or secondary review at the airport.

Your I-829 letter continues to serve as proof of status. The I-551 stamps are not required. Do you have international travel planned? If so, and you really want to have a stamp in your passport, there are certain USCIS offices in which you can walk in to receive services for emergency situations. Discuss with your attorney.

Try walking into another office. They will usually take walk-ins early in the day, especially for just a stamp.