Yesterday, I played someone from the Bahamas for the first time but did not get the Bahamas stamp in my Passport. We played a full game all the way to checkmate. Why is that, and how do I get that stamp?
I would write to support@chess.com. They might be able to help. Please include a link to the game you played.
It might be a bug but I don't think it is because you would see a lot of other forum postings about it.
Today I received a message from support@chess.com:
Thank you very much for reaching out to Chess.com Support. I hope you're enjoying your day! 
I checked your account and you're right. You should have the Bahamas passport stamp unlocked! I've contacted our developer's team so they can get it unlocked for you as soon as possible and so they can look into why this isn't happening automatically! You should have this unlocked no later than Thursday morning!
Thank you so much for your help with this! Please let me know if you have any questions or concerns!
Kind regards..,
Brenda
Assistant Director of Support
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We will see what happens in the next couple of days.
cool 
The trend continues. I just played someone from Antigua/Barbuda for the first time but did not get the Antigua & Barbuda stamp in my Passport. We played a full game all the way to timeout. First it was the Bahamas. Now it is Antigua & Barbuda. I see a trend and have once again reported it to support@chess.com.
See https://www.chess.com/game/live/29126342263.
Thursday morning has come and gone. The Bahamas passport stamp is still locked. Time for another note to support@chess.com. 
Today I received a message from support@chess.com about the Antigua/Barbuda and Bahamas passport stamps:
Thank you for reporting this!
It isn't just the two, we have a bug that's causing members not to receive their stamps. We have placed a report to our developers so that this bug gets resolved as soon as possible!
I'm very sorry for any inconvenience! Thank you so much!!
Brenda
Assistant Director of Support
Apparently the problem is more widespread than I thought.
Well, finally we know what they mean by the "Bermuda Triangle".
Lol
Today I received a message from support@chess.com about the Antigua/Barbuda and Bahamas passport stamps:
Thank you for reporting this!
It isn't just the two, we have a bug that's causing members not to receive their stamps. We have placed a report to our developers so that this bug gets resolved as soon as possible!
I'm very sorry for any inconvenience! Thank you so much!!
Brenda
Assistant Director of Support
Apparently the problem is more widespread than I thought.
I think this affects me too. It's a bit minor for me as I'm more into achievement collecting; however I know quite a few people who are into collecting passport badges
Yesterday I followed up. Here is their response:
Thank you for your continued patience! I had to wait to reply so that I could speak to our developer who is in charge of this. Currently, the issue is that this isn't the only achievement/passport we are having trouble with. They are currently in the testing phase of it. I know it's been a while, but we do have other things that we have to set as a priority and they are going as fast as possible to get to our other "nonpriority" items. I have been told though, that once this is fixed I will be able to refresh and unlock this achievement for you!
Please continue to bear with us as we work through this and get it resolved as soon as possible!
Thank you so much!
Brenda
This has happened to me with 4 countries. Rough, huh?
same thing just happened to me and my friend. the bug must be running around again. I think I'll shoot another message to the website
I think same thing happened to me today. must you send email from private or email or is there a function in chess.com to contact support?
Chess.com has a function to contact them, but I prefer email. That way, you have a “paper trail”.
Yesterday, I played someone from the Bahamas for the first time but did not get the Bahamas stamp in my Passport. We played a full game all the way to checkmate. Why is that, and how do I get that stamp?