What device do you own? Does it support personal records in cycling? Also try to check the page Personal Records in Garmin Connect Web, whether some records do not wait for approval. And you can also assign a PR manually from the detailed page of the concerned activity, in GC Web (see the option Set as PR in the cogwheel menu).
The user manual for FR 220 mentions running PR's, but there is no reference of cycling PR's, hence it is possible they are indeed not supported. You can still try setting the record manually:
