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Replicated transactions are waiting for next Log backup or for mirroring partner to catch up - Issue in SQL Server Replication

Hope you read my earlier post of "Replication components are not installed on this server" issue, you may like it. One day suddenly replication went to high latency and I clicked it during monitoring. I opened the replication monitor, during analysis I found one message which was showing latency from publisher to distributor due to some issue. The message is as follows,

Replicated transactions are waiting for next Log backup or for mirroring partner to catch up”.

As per message i checked the transaction log backups were happened or not, checked it and log backups were happening . Finally one option is pending to review and it is mirroring. I checked the status of mirroring  and see the  principal database went to synchronizing mode. May be mirroring went in synchronizing mode due to heavy or so many transactions in the route to apply at mirror database. So replication is waiting  to be synchronized status of principal database. I exactly do not know why replication went on waiting even transaction log backups were happening. I checked online solution and received some of the solutions from here and it suggests following,

1. EXEC sp_replicationdboption 'PublisherDB','sync with backup',false
This means that not need to backed up of all transactions before being delivered to the distribution database. Please visit this option here, which sets a replication database option for the specified database. This stored procedure is executed at the Publisher or Subscriber on any database.

2. Enable trace flag 1448
After this setting the Log Reader Agent can continue replicating changes regardless of the mirroring state. Please read more here.

I never applied these suggestions. Replication and mirroring both are using transaction logs and this could be the reason why replication was in high delay status while mirroring was stuck or in process to synchronize the mirror database. So I turned off mirroring and monitored replication status. Finally replication was succeeded to remove the delay and applied all pending commands. Then I configured to mirror again after doing with replication sync.

Conclusion : We have two options, either to wait for synchronized status of principal database or turned of mirroring, getting replication synced properly and reconfigure mirroring again depends on priority and importance. It will be better to go for correct solution to avoid such issue. But question is here, why replication went on waiting for a synchronized of mirroring even transactions log backups happened while? I would like you to share if received such issue and solution or any opinion which you applied to resolve it. This may help to me and all people facing the same issue.