A couple of things to keep in mind about the online records at Family Search:
(1) Not everything at the FHL library has been digitized for a locality.
(2) The titles may not always reflect all of what is in the record (a good example is the first volume of Aguascalientes baptisms and marriages: they are all in one volume, but the list of titles only indicates one.) This is especially problematic with the early matrimonial investigation records.

It is often useful to check the FHL card catalog to see what the library actually has. In doing this you will find that there is apparently a gap in the matrimonial investigation records in the early 1760s, except for Indians, which apparently exists. It is possible that the records for the Spanish are mixed with those of the Indians, but considering the large time period covered by the Indian records, seems unlikely. But it is always worth checking.

There is always the unfortunate possibility that those records do not exist.

George Fulton
Pleasanton, CA