It looks like some of the Freedom records for 1779 may not survive.
The records digitised on Ancestry are held at London Metropolitan Archives. The LMA catalogue jumps from COL/CHD/FR/02/1068 (for September 1778) to COL/CHD/FR/02/1069 (for October 1784), implying a gap of 6 years.
You could drop LMA an email to check, as this sort of query is generally answered free of charge.
ask.lma@cityoflondon.gov.ukADDED - Ancestry does claim to have 620 records for Freedom Admissions in 1779, and a random check shows that some are from that year, but many are wrongly dated. Probably best to ask LMA for advice.