Retain functionality works inconsistently

Version: 3.3.3
Deployment Config: Windows 11, OpenJDK 21.0.5, Standalone mode, Default configuration
Tools: Using Mqtt-Stresser for pub/sub

A Steps:
1. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 1, Retain true.

Behavior:
No message being retained.

B Steps:
1. Delete Data\retain_data folder
2. Start Stand alone server
3. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 1, Retain true.

Behavior:
Only 10 topics are retained and the rest do not get retained

C Steps:
1. Connect 50 Clients, each client publishes 1 messages on 1 Topic (test\client-1, test\client-2, test-client-3....) with QOS 0, Retain true.

Behavior:
It seems that only 10 messages every get retained, is this a configuration flag

Start by reproducing the three scenarios on Windows 11 with OpenJDK 21.0.5, standalone mode, default configuration, and Mqtt-Stresser. Compare retained topics and messages before and after deleting Data/retain_data, then inspect the relevant retention configuration and storage behavior; done means all expected retained messages are consistently available.

Written by the indexing model from the issue text.