Event subscriptions not persisted to database

**Describe the bug**
Recently we had three Workflows that started with WaitFor steps not proceed after the corresponding events were published. After restoring a database snapshot to one before the events were published and querying the WFC tables we were able to determine that the event subscriptions were never persisted to the database.

**To Reproduce**
Steps to reproduce the behavior:
I have not managed to reproduced this error.

**Expected behavior**
Subscriptions should be persisted to the database.

**Additional context**
- Using SqlServer for persistence
- WFC version is 3.8.1 on .NET 6
- The three Workflows started at nearly the same time
- No errors in the logs to indicate any issues persisting the data
- Suspect it may be related to issues supposedly fixed by #1081, though we don't see any logs that say the service is stopping until about 30 minutes after the Workflows were started (This being caused by an idle timeout which we are going to disable).

If there is any additional information we can provide please let me know.