This happened to me when requesting a Visa packet in February 2020.  I first requested the index search.  I received a letter stating the index number was found and I could then request the record search.  After paying the second $65, USCIS was not able to find the record.  The online case status read "Closed".  The letter I received from them read that the record was either missing or lost from their record holdings.  They encouraged me to wait a few years and try again, since they are constantly finding records in the wrong places (my words, not theirs).  They refunded my $65.

You will receive a letter soon indicting the problem.  If not, email Genealogy.USCIS@....  I am dealing with them now on a payment I made in August that they have no record of and hence did not send me the Visa file.  After I showed them proof of payment, they are now doing it.  It is nice that they acknowledge their problems.

Best of luck,

Marlise Gross
Cherry Hill, NJ