I will add one key suggestion:  Make sure that the issuing bank (not the brand, like Visa or Best Buy, or any non-bank name) is in the US. You can find the name of the issuing bank on the back of the card, or on the attached paper that holds the card.  Look for something that says: "Issued by_______________________ bank." Then google that bank name if you do not recognize it.  

 
Non-US issued cards are always treated as high-risk (due to the abuse of these for money-laundering) and are likely to be blocked.  

 
Finally, you can always set up a Seeking account with a throw-away (but real) email address then contact Seeking support (through their chat bot) and ask if your gift card will be accepted.  

 
Life is good

 
The Cat

What is SA's official corporate address (for payment purposes)? Pre-paid CCs in the US will usually say whether or not they may be used for non-US payments = another protection against money laundering or transferring money to Terrorist organizations (not to be confused with TERorist organizations  .  
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It USED to be that you could register a pre-paid CC (Visa was the best choice) with fake info for simple US payments but international payments required REAL banking info = SSN, real name, real address, etc. before international payments could be made at all (and some pre-paid CCs won't do them at all).
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Read the fine print on the cardboard outer package and look for US vs Int'l restrictions.

I didn't go through the steps Herb did but I wasted $250 on a GC and still had to use a real CC.