$$$ AGMs should have more care than common flooded batteries.
1. Read the manuals online.
2. Use a accurate voltmeter on the battery terminals, plugins even if accurate reflect the voltage at the plugin not at the battery.
3. It doesn't appear that your charger has remote voltage sense or temperature sense so it's likely not charging the AGM correctly.
4. Battery charging voltage is lower for hot batteries.
So you may not be charging your AGM correctly based on voltage and temperature. Plus you may not be able to change the charger parameters to match the AGM. Or it may be OK, read the manuals.