When planning to upgrade your Mautic instance(s), it’s important to consider the third-party plugins you’re using. Some plugins might not function properly with the new version due to changes that could affect their compatibility and features.
Be sure to check the plugin’s GitHub page or contact the developer directly to confirm if the plugin is compatible with the latest updates.
Did reinstalling the plugin solve it? GitHub - pm-pmaas/etailors_amazon_ses looks like it’s being actively maintained, but we haven’t testet it yet and it doesn’t mention 5.2 on github.
Depending on upgrading method a bit but I think esentially all methods invoke reinstalling to core files, so when you do that Ses plugin gets deleted most likely.
Always do fullbackup of dattabase and source before any upgrade, then upgrade and move third party/custom plugins back