Release 0.2.X+ of the plugin has added a new tag requirement in order for the plugin to know which data to pull in from AWS Secrets Manager. Existing secrets without this tag will not be pulled in. I would classify this as a breaking change and a note should be added to the README.
This can be tested by installing version 0.1.4 and only specify a tag that one can use to Filter the secret against. It will come in. If you then upgrade to 0.2.0 or higher and create a similar tag without the necessary credentials type tag, then it will appear.
Interestingly enough, this does not impact recognizing if the secret key has been deleted.