In the database asteriskcdrdb, there’s a table called ‘cdr’. From that server, log in using ‘mysql -u root asteriskcdrdb’ and select the records that coorespond to the dates and times you are looking for.
Check to make sure the unique IDs are getting set.
If some are there and some aren’t, there are per extensions settings for making recordings. There are also “on call” sequences that turn recording on and off. Finally, if your users are using UCP, they could be deleting the recordings from UCP.
There are lots of places where recordings can go wrong. If you can look through the logs, you can verify that the recordings were created in the first place. If they are, but they aren’t getting logged in the cdr records, there’s something going on. The rest is just detective work and guessing.