fix: Unable to populate additional fields because the itemtype is missing from DB request

[ccailly]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

Description

Ensures that the itemtype is explicitly set in the plugin fields data, rather than relying on the default value in the database (this technique no longer works since 11.0.3 of the core)